They are not a Colt, LMT, or BCM, but neither are they DPMS, Oly, or BM.
Over the last three years we have purchased 720 S&W 14.5" M&P-15 rifles. So far we have not had any issues with these rifles. I also know of several other large state agencies across the US that have purchased large quantities of M&P-15's and they are not having any problems with their rifles. There are also several large local agencies that have made large purchases of these rifles and they are not have any issues with the rifles.
IMHO based on my experience with the number of M&P-15 rifles that I have handled, I would say that you made a good choice.
Just finished teaching a 40-hour patrol rifle operator class for my department, using the S&W rifles, and we had nary a problem. Our only issue was the old junk magazines we give to the students for the course, so as not to dent up their duty mags, but it gives the students practice time on transitions and tap-rack drills.
I've had my job-issued S&W rifle for about 2 1/2 years now, one their early models, and it shoots like a champ. Probably 3000 or so rounds through it and shoots fantastic; I honestly can't remember the last time I had a malfunction with it, if ever. Our rifles were bought completely stock, but our department has upgraded them over the years. Now we have fixed Troy rear sights, Troy drop-in 4 rail systems, and streamlight flashlights. We are looking into getting Aimpoints in the near future.
The operators love the Smith rifles and they have been carried now for two years with no complaints. Students burn about 1100 rounds during their basic operator course, and qualify twice a year with about 260 rounds or so per in-service, so if there was any issues, we would have found them.
I have no problems trusting my life and the lives of my fellow officers with these rifles! Two thumbs up!