Yep, agree with u. Zero issues with speedmod, with galaxian sometimes the wifi turn on and off by itself. i'm thinking to try JVR, but some debates that its got some modified files from JVQ and one thing i found kinda weird, how come the darkyy rom crew can be associated with samfirmware??
Well, for both your questions, i think if you disable (untick) your mobile network and the data roaming, i think u're good to go. wifi doesnt affect your data plan.
GalnetMIUI is one good rom, have eye-candy looks( kinda iphonish), smooth and stable but no fm radio, choppy 720p video playback. for CM7, the rom is pretty simple and all the bugs from MIUI comes from Cm7 built also, but the big advantages is its lagless compare to any other samsung rom and cm7 have kinda simple like AOSP looks.

yep, and the recording too also in 720p is not good as in stock samsung rom. what rom u're now on? but if cm7 or miui team will ever iron those bugs out, i'm never ever gonna turn my back to samsung rom anymore.

i'm tired of waiting for official 2.3.4 to come out to our sgs. i feel like want to rompak one GS2 already.