My sons play online and they've not noticed much difference. They 'host' alot more and there's no dropped connections when they do that's about it
When I play I still lose ! but thats because I'm rubbish.
not for me!! (again 'cos any host advantage is undermined completely by my lack of talent)
although my boys reckon there is some play advantage - I've simply not experienced it.
just asked them ; they say they win more . But on some games (not sure about fifa) the online servers compensate for lag and try to even it out.
On COD2 only the very 'slow' players really have much of a disadvantage (so I'm told)
but in my experience : infinity will give you a fast, consistent line where you host most of the time and which so some games will give advantage or at least no disadvantege and where other people in your household can do their thing at the same time.
e.g. earlier today my boys were playing something online and I was downloading a HD film - they didn't notice.