I never trusted a gun firing in front of my face either, but after tens of thousands of rounds, in many dozens of guns, nothing blew up yet.
& I have loaded some blue pill hot loads that have caused guns to fail.

Bullpups give the 'easy to handle in close quarters' length of a sawed off shotgun, with a full length barrel.

As for the Saiga magazine problem.
I bought larger capacity magazines for my .410 Saiga.

The .444 & .45 long colt conversions require custom magazines.
[link to i98.photobucket.com]
People at the Saiga-12 forum post pics of their custom work and discuss modifying 30 & 40 round AKM mags for their Saigas.
A drum mag

[link to www.gunaccessories.com]

SAIGA .410 15 Round Factory Mag

BTW Saiga is the cheapest 7.62 NATO carbine available

SAIGA 308 25 Round USA Made

SAIGA 12GA 10 Round Synthetic Mag ProMag
SAIGA 12GA 12 Round Synthetic Mag Surefire Mfg
***
edit to add:
Tromix
[link to www.tromix.com]
Video links on page

>Our flagship product line is the insatiable Micro-12 gauge sporting an 8” barrel, HK battle sights, and a Tromix shark brake door breacher. Our Micro shotguns will cycle low base target shells as well as the stoutest 3” magnums. Feeding from a 10 round box magazine,..
With the advent of the detachable box fed Tromix Micro-12 gauge, you have an UZI size weapon, with the reliability of an AK-47, packing the knockdown power of a 12 gauge while still maintaining a full 10 round capacity <