Sorry, I'm a bit late to this thread and haven't read all the posts.
My 2 penneth, I have had Infinity for 18 months and there is only myself who uses it, I don't even have a phone on the line
The first couple of days after it was installed it was fantastic (on Battlefield bad company 2 for PC) shortly after it seemed to never be as good, no idea why.
In that time the speeds have been good, pings generally good, as in 30ms to German servers (BF3) but my overall "feeling" is one of it's not quite doing what it says on the tin.
64 player servers seem to lag quite often.
My contract is up now so I (read the wife) can't justify a second line for my gaming, I don't feel as though I am leaving behind the nirvana of gaming connections and I am going to fall back on our VM conenction.
My 2 sons never complain about lag, to me anyway, on VM so that suits me.