Not sure. Usually about 1,000 or so on around the globe when i go on. Not sure about live though. I suspect Live has more because not too long ago Bungie announced their 7,777,777th H2 game played or some crap like that. Xlink in my opinion gives you more freedom. I hate random matches that often repeat in a single sitting of LIVE. And at least people on Xlink that mod, use mod rooms for it. I think the folks on Xlink and XBC are more considerate. But thats just my opinion I could be wrong!
idk but i like xbconnect way better than xbox live because in xbconnect you get to play more than one game with different people instead of just one game than everybody leaves
I use KAI, there are alot users there, i like it alot better than xbc, Live will have the majority of peepz, not alot know about KAI and xbc, but i find KAI is easy to use and also the fact its built into XBMC