I would not do it. We are not allowed to post links to other forums, otherwise I'd send ya to a thread about the 9mm M&Ps as of late.
Apparently the 45 and 40 versions do not suffer from accuracy problems... But there are a fair share of complaints about the 9mm M&Ps. The accuracy seems to suck on them, and people are trying to fix the issues. Some are putting in aftermarket barrels and stronger recoil springs. Apparently, there is a lock time issue. The threads about it go on for pages, and it seems to have supporting documentation - not just some people's opinions.
I bought an M&P 9mm Shield, and I really like it. When the M&P line comes out with the same trigger as the Shield - I'd like to buy a fullsize 9mm M&P. But not with this issue until it goes away