Given the recent posts about the MD SP and the PX4's, I'm thinking you might be able to do considerably better on a PX4 soon. Perhaps some police trade-ins...
On the other hand, I like the M9 so far. She's a big girl, but I still iike her.
I think half of my posts on MDS have been defending the PX4. It's certainly a personal thing, I bought it over the other "plastic" guns because of the ergonomics, the standard medium grip fits my hands perfectly. The DA trigger pull is a little strong, but it *IS* a DA pull. The SA pull is nice. I shot in an IDPA match with it last month and did very well, even though almost every other shooter was using a striker-fired pistol, I finished 5th out of 37 on the course that required the most accuracy... and the guys above me, all IDPA veterans with Expert and Master ratings.
That said, I probably won't buy another PX4. I'd love to find a 90two or 96FS with the Inox slide, though.