Don't judge games on demos. Both full version of Ren and BF ran a lot better in the final version then in the demo's on my system. At the time it was the lower end of the sys req's on both games... but now that my computer has caught up with the games it just looks/plays damn good. Ren's netcode is a lot better now then when it was released, but I still think it's best on a lan. BF I havn't touched in a while thanks for UT2003 and NS.(mainly NS)
Renegades when you connected to a good server has always been a great stable game. Their main problem was that everyone was trying to run servers from their homes and it really needed a big machine/connect to handle the load.
Also the main reason I havn't been playing it lattely (Like a lot of games) is because you need to put the damn CD in the tray every time you want to play. Last Time I went "Oh I think i'll jump into a quick game", being greated by a "No CD found in Drive" error just killed my urge and sent me back to another game that I didn't need the CD for.