Like I said in my PM Texan, if I had to do it again and didnt already own the UBR, Id go with the F93 myself... I pretty sold on putting one on my SBR when I eventually do it..
I have the Magpul UBR stock on my DPMS 3G. it has a heavy SS 18" barrel. It is a heavy stock, but it balances the rifle perfectly. Keep in mind how the rifle will feel and where your cheek weld will be. It is a great stock.