1. How easy/difficult is it to get mags out considering they ride close to the body?
It is no trouble to ge the mags on your off hand side; it takes a little more of a reach to the the mags on the other side of your body.
2. How's the quality ?
SO Tech gear is made to about the highest quality standards possible.
3. Is it difficult to aquire a good shoulder weld with it on ?
There are no bulky pads to get in the way. There is not a problem with shouldering the buttstock.
4. How is it in the prone position?
As good as any other gear that you have on your chest. If you are propped on your elbows and your chest rig is worn on your chest (and not lower on your mid section), then you wont even notice it.
5. What additional pouches / mag pouches would work well with this system.
Anything with the MOLLE/PALS attachment (Tactical Tailor, Paraclete, SDS, S.T.R.I.K.E.)
6. And finally I see there is a Hellcat 3 system with the release buckle in the front. I understand its convenient BUT is it worth it?
I prefer the one piece, original Hellcat.