I shoot a P16-40 (older model) and have done very little tweaking on it - yes some parts replacment but everything total between 100-200 USD.
I have played around with a STI and have found it getting used to.
IMHO it boils down to peresonal pref. Top guys win with Tanf., BulM5, Para, S_I, and what else.
I don't like the top-heavy feel of plastic guns when they run low on ammo and my Para runs 100% and is more accurate than I am.
Pick what you like, then check with the bank mang (some call them wife... ) and get it....