Glock or Colt 9mm AR lower?

[Colorado Osprey]

I understand the reasons for making a dedicated 9mm using the Colt design pistol upper. But have your considered a Oly design which Colt multiple times has tried to acquire so they could make those instead of their own? No dedicated lower needed. The new Oly mags are plastic but STEN mags are still plentiful and cheap if you use a block.

I am running Oly design and a couple of my friends have went the Colt design and sold them to get the Oly design.

The only real drawback to the Oly design is you dont get to fuss with it to get it to run reliably. They run great out of the box.