Wish more companies would offer these. It would make for a very compact gun without having to go thru the NFA bs. The Tavor has one, but its heavy and bulky. If you are listening Keltec make one with the downward ejection. Also, offer it in glock mags please.

9mm AUG conversion kits are out there, they are no longer being imported though. There's also the JARD carbine, it uses glock mags.

And even the Kel Tec RDB (5.56) lists for about $1300, so if they ever made a 9mm version it wouldn't be cheaper.

FWIW someone (Tower Armory?) is releasing a bullpup kit for High Point carbines this spring. Depending on cost I may try one out on my 4595. Estimated cost is $200 - $300.
Yea, that means it's a $600 High Point. But when I bought my first AK years ago I was looking at a grand to make an AK bullpup. It's a great design but admission to that club isn't cheap.
And Sub2ks, CX4 Storms and High Points have magwells in the handle which make for pretty short packages already.

Jard makes one with a similar eject to the keltec. It's one ugly rifle.

They look much better in person, especially in black.