I handled it at SHOT show this year with both 7.62 and 5.56 uppers. I think it's a cool design, but ultimately not for me. I already own a 308 AR, and would be happier with a seperate 5.56 rifle. The bulkier, heavier lower(vs an AR15) feels clunky and cumbersome with a 5.56 upper installed. At the expected price you could get into two rifles, and having to change out the buffer and spring along with the upper and magwell block means the 901 is not really a quick change operation. I don't see much advantage. At $1400-ish it might appeal more.