It's not just p2p which is being shaped, I can't even get single thread http stuff (downloads, speed tests, TBB test files, etc.) to go faster than around 4Mbps per thread between around 7am and midnight.
The only thing which will push the download speeds right up to maximum are multiple threads (and we're talking 20+ simultaneous threads needed to get full 80Mbps line speed).
In all honesty, if you can get close to 15Mbps+ on ADSL2+ or don't really need the higher upload speed (of FTTC) forget Infinity and stick with ADSL2+.
I'm still reasonably happy because I switched from a very long line which could only do around 4 to 4.5Mbps on ADSL2+.
If I'd have switched from a 16Mbps line I'd be seriously p'eed with BT.
Ade
vDSL2 FTTC Infinity with BT
DL Sync 80Mbps
UL Sync 20Mbps