Disadvantage of Transparent Proxy?

Could someone list me the disadvantage of an ISP which has Transparent proxy? I am churning to a new ISP (mainly because it will not cost me a cent to get a way better plan) and i know this one has transparent proxy (its on the broadband forum)..
Will it affect my speed? i can still log onto the private torrent website? any hassle free solutions to go about it?

oh snap some few says they dont let u sign up from behind a proxy

You should still be able to login to private torrent sites. Fingers crossed they're making use of the passkey system. If sites like detected a shared IP, it's likely someone else will have used up your limit.