Matt,
3 Urgent features:
+ Archive for PM's sent, more important than those received, which you can choose to delete or copy at leisure...
+ Ability to fully view 50 posts on the page, when hitting a random post number and doing a look around... This is available on both SI and RB and very useful...
+ Spelling should also be high on the List, as I see many posters struggling... I hear, the smart ones now compose their messages on RB to spell check them before posting... Why give RB more Business?...
JMHO, FG