Both the idea that Legolas is a relative inexperienced "baby" among Thranduil's many children and the idea that he would have little to no battle experience prior to LOTR (or the BOFA) is highly unlikely and, if you're paying careful attention to dialogue and character in LOTR, almost ludicrous.
As pointed out before, Legolas refers to other members of the Fellowship as "children" and he does mention that he has seen many on oak from acorn to ruin. That statement does not imply many oaks that were all the same age dying in the same relative decade or so; instead, it implies that he has witnessed the entire process (from acorn to sapling to dying tree) many times over. Since oaks can live more than 200 years, this elf is seriously old. More importantly, Gandalf himself refers to Legolas as "a dangerous warrior." One thing about Gandalf is undeniable; he only says what he knows FOR SURE, and he is not the kind of soul who would make that kind of declaration on someone else's say-so. Therefore, it is likely that Gandalf has first-hand knowledge of Legolas' battle prowess. And why wouldn't he since Gandalf has kicked goblin and orc butt alongside the elves often. So Legolas at either Dol Guldur or BOFA is more than reasonable.
I also find very weak the claim that Legolas would somehow KNOW Gimli at Rivendell or be immediately reconciled to Dwarves if he had fought in BOFA. Nations and peoples who hold tepid at best relations with certain neighbors have often joined together to put down a common enemy, only to continue to disdain or misunderstand one another's cultures shortly after. As someone earlier stated, whether or not Thranduil actually reconciled with Thorin and company afterward, it doesn't mean that general mistrust and disapproval would not remain between the two races. It is much more likely that it would.
When Legolas speaks up to defend the elves' loss of Gollum at Rivendell in LOTR and a dwarf (Gloin?) snipes about not getting so good a treatment when they were "guests," there is neither recognition or lack of recognition of the Dwarf in Legolas' reply. He could know to whom he is speaking or not. No judgment can be made.
Having said all this, I find no problem with Legolas appearing in either place. Instead, I think it's another interesting way of tying together threads.
Besides, I know I read somewhere (I think it was a biography of Tolkien written by his son) that the character of Legolas was a very late addition by Tolkien into the storyline of LOTR. If I remember correctly, multiple drafts without him had been worked over before Tolkien decided that, without him, the elves were merely this shadowy and mostly absent presence in the story. He felt they needed some up front representation. This late entry, however, would explain that, of all the main LOTR characters, Legolas' character and family background is the least fleshed out. Of all the nine, he is the only one who lacks a story; in fact, I would argue that the friendship between him and Gimli is much more Gimli's story than his because the whole thing began with Gimli's admiration of and allegiance to Galadriel. It's as if he suddenly saw the magnificance of elves.
Of course, I think this is Tolkien's major drop here. I often felt that he was always concerned that if he showcased an elf much at all, the reader's fascination would quickly overshadow the men characters. And not just Aragorn, but also Faramir and Eomer. Personally, I never cared much for the whole Boromir, Denothor, Faramir bit. How come the elven women had to always be smitten with men. How about Eowyn growing fond of Legolas. That would have been a nice twist. Anyway,...I digress.
As pointed out before, Legolas refers to other members of the Fellowship as "children" and he does mention that he has seen many on oak from acorn to ruin. That statement does not imply many oaks that were all the same age dying in the same relative decade or so; instead, it implies that he has witnessed the entire process (from acorn to sapling to dying tree) many times over. Since oaks can live more than 200 years, this elf is seriously old. More importantly, Gandalf himself refers to Legolas as "a dangerous warrior." One thing about Gandalf is undeniable; he only says what he knows FOR SURE, and he is not the kind of soul who would make that kind of declaration on someone else's say-so. Therefore, it is likely that Gandalf has first-hand knowledge of Legolas' battle prowess. And why wouldn't he since Gandalf has kicked goblin and orc butt alongside the elves often. So Legolas at either Dol Guldur or BOFA is more than reasonable.
I also find very weak the claim that Legolas would somehow KNOW Gimli at Rivendell or be immediately reconciled to Dwarves if he had fought in BOFA. Nations and peoples who hold tepid at best relations with certain neighbors have often joined together to put down a common enemy, only to continue to disdain or misunderstand one another's cultures shortly after. As someone earlier stated, whether or not Thranduil actually reconciled with Thorin and company afterward, it doesn't mean that general mistrust and disapproval would not remain between the two races. It is much more likely that it would.
When Legolas speaks up to defend the elves' loss of Gollum at Rivendell in LOTR and a dwarf (Gloin?) snipes about not getting so good a treatment when they were "guests," there is neither recognition or lack of recognition of the Dwarf in Legolas' reply. He could know to whom he is speaking or not. No judgment can be made.
Having said all this, I find no problem with Legolas appearing in either place. Instead, I think it's another interesting way of tying together threads.
Besides, I know I read somewhere (I think it was a biography of Tolkien written by his son) that the character of Legolas was a very late addition by Tolkien into the storyline of LOTR. If I remember correctly, multiple drafts without him had been worked over before Tolkien decided that, without him, the elves were merely this shadowy and mostly absent presence in the story. He felt they needed some up front representation. This late entry, however, would explain that, of all the main LOTR characters, Legolas' character and family background is the least fleshed out. Of all the nine, he is the only one who lacks a story; in fact, I would argue that the friendship between him and Gimli is much more Gimli's story than his because the whole thing began with Gimli's admiration of and allegiance to Galadriel. It's as if he suddenly saw the magnificance of elves.
Of course, I think this is Tolkien's major drop here. I often felt that he was always concerned that if he showcased an elf much at all, the reader's fascination would quickly overshadow the men characters. And not just Aragorn, but also Faramir and Eomer. Personally, I never cared much for the whole Boromir, Denothor, Faramir bit. How come the elven women had to always be smitten with men. How about Eowyn growing fond of Legolas. That would have been a nice twist. Anyway,...I digress.