>>64168248
>The mags and ammo are also (obviously) the same bulk and weight as an AR's.
I would consider the ammo commonality to be a plus. 5.56 mags are smaller than P90 mags, no? And honestly, the P90 still makes for a fine PDW in it's own right. It an overall length of 19.9" and a 10.5" barrel, which is even smaller than a micron, but without the loss of much barrel.
Imagine if the P90 didn't have to bother with using a round that fits in a pistol grip. That could be something special.