Yes, they all run well. You can check out some vids on my youtube channel:
https://www.youtube.com/user/c3junkie/videos?view_as=subscriber
I like the MGI AK mag catch better than KS47 or original AR-47 lower by Michaels Machines (I have one of those also). Those are both flapper style. The MGI design is push button...AR style to release the mag. Works very well.
Now the MGI AK magwells were designed around the use of steel mags and drums and the polymer mags may require some fitting. I pretty much run mine with drums all the time....no fitting with drums.
For 9mm, I would highly recommend going with the CMMG radially delayed blowback and skip all the straight blowback configurations.
https://www.ar15.com/forums/Armory/Full-Auto-CMMG-Guard-Tuning/23-494385/
You can also check out
https://www.windhamweaponry.com/firearms/rifles/mutli-caliber-systems/
I think they licensed it from MGI. I know friends that have MGI lowers and bought Windham magwells and they drop right on.
The picture I posted above is pretty dated...since going to the CMMG RDB system, I use a standard AR magwell and just use the new MEAN Arms Endomags, so not using the 9mm Mag block anymore. I also sold my GG magwell and setup and wish I never did that. However, I really like last round BHO and you don't have that with GG mags which is one reason I let it go.
So for me, I really just use the AR magwell and the AK47 and AK74 magwell (which is very hard to find these days).
So if you are really interested in the AR magwell and AK47 magwell, may not be worth it to you.
However if you like to tinker....the MGI is the ultimate...
I am also getting a 3D printer and thinking about printing my own magwells...like a DPMS GII to run .308 and maybe one to accept Scorpion mags and then use the CMMG Radially delayed blowback in 9mm with it.