I've recently been considering one of these #11600 M&P 15T rifles.
M&P(R)15T Tactical with M-LOK(R) | Smith & Wesson
If this is what you can get at $850, it sounds to be a good deal.
The info I posted indicates a free-floating handguard and is advertised at 6.7 pounds.
I currently have a very similar Springfield-Armory "Saint". My LGS had the Saint in stock the day I bought, and it would have been a tough decision if they had the #11600 M&P 15T for sale at the same time. I might have bought both at the same time, if it did have both for sale.