I think most of the people against Barnes were "purists"

, who thought that Caspian should have been younger and blonder as in the books. Not to mention they felt his character was reverent enough to King Peter

. In any case, he was brilliant as the FILM version of Caspian. And thinking about how he played Caspian, I think he's at least in the running for Beren.
If Keynes were much older I could see him as Gorlim. But it's a small part as he would be killed off very quickly.
I just threw the Merlin Guys in because I personally think they are awesome

. But it's a bit of a low budget programme, so not everyone might feel as I do.
Speaking of Merlin, how about the guy that plays Uther (I think his name is Anthony Head)? Perhaps as Barahir?
Russell Brand is a bit out of left-field, as he usually plays humourous roles. However his role in Primeval expanded as the series went on. If you find one of the later episodes online, check it out and let me know what you think. I've seen him with long hair and a scraggy beard, he looks like stepped right out of a Medieval or Renaissance Fair.
GB