I havent used either in a long time.. 2+ years.. but I belive MS's version is formerly battlecom, which was a freaking nice program. It had way more features then RW had at the time.
As for bandwidth.. thats not to big of a concern. Battlecom used to have multiple quality settings.. Different compression rates.. So if you were on a 28.8k modem and trying to play, you still use the program, but it wouldnt sound so hot.. or it you had a phat pipe, you could jack up the quality.. RW only had the single setting if I remember correctly..
I think you could try both and see what you like best.
RW always causes weird issues for me. I play TFC, and I cant prime a grenade if I have RW on
Perhaps you had the same key binded for both the gren and RW? It really should work without a hitch with TFC (if you set it up correctly) since it was kinda developed around TF and TFC..