I have an original SD9 and a SD9 VE. Both with new sights and Apex trigger kits. As a stock guns the SD9 VE is one of the BEST value guns available by any maker. A $500 gun at a $325 price tag. Glock 19 in size and just as accurate / reliable. The stock trigger is stiff but manageable. In the configuration mine are in, with 10-8 rear sights and tritium front sights as well as Apex trigger kits, they are excellent guns. My SD9 with the $20 Apex triggers come in at around 5.75lbs and are very smooth. Reset is a little long but not unreasonable at all. Galloway Precision is also working on a kit that promises to be even better.
The SD's are smaller and thinner than the full size M&P they carry like a dream. They also perform just as well as their more expensive brothers. I am an M&P guy through and through, but the SD line is more than just a cheap amalgamation of the Sigma and the M&P. On it's own it is a very good gun. I have well over 1,000 rounds through my original SD9 and it show no signs of internal wear.