I seem to be in the minority here, but I changed back to M96 and vertical grip. Two reasons really. I am a lightweight freak, and the M900 weighs 19 ozs. Having said that, I gotta call the weight good weight, sometimes. When using the hand on the M900, it sure doesn't seem the carbine is that heavy. Superb ergonomic design here, believe the hype. My problem is when I change grips to the mag well. That weight is definitely noticeable, and turns into bad weight. The KAC grip M96 combo weighs 14.5 ozs (the Tango Down will only add an ounce). So it's not that big of a deal, but for a freak it matters. The better reason for me was accidental light discharge. I don't practice enough with using the M900 to prevent it. With the M96 and a thumb button, not a pressure pad, no discharge of light unless you intend for it to happen. It ain't going off unless I move my thumb over to it and press. It's just much easier to control, for me.
Of course, you just gotta get both and try it out, it's the ARFcom way. Thanks.....Chad