Folding stock, easily swapped barrels (5.56 to .300BLK and back again sounds fun,) and replaceable wear point on the upper. I'm hoping the removable forward assist assembly also means there'll be an option to just slap a plate on there and get rid of it.
I've been contemplating what kind of rifle I could leave in the truck this time of year. Today is insanely mild (if it gets any warmer, stuff might actually melt!) but just a week ago I was doing a felony stop in -30ºF windchill. With that in mind, I've tossed together some parts I had around the house, and ordered a new stock to throw on it.
BCM middy upper I won in a raffle a few years ago, fixed rear sight off the M&P15-22, and some Magpul grips, and their Fixed Carbine Stock, which has the same length of pull as what I set collapsible ones anyway. No electronics to die in the deep-freeze.
The plan is to keep an eye on the weather, and swing over to the range one of these days when it's freakin' cold out again, with the gun in the back so it stays nice and cold. I'm just debating what lube to use (the last time I was shooting ARs in -20º or lower temps, it was noticeably sluggish with CLP.)