I've handled them at the SHOT Show. They are very well made and yes, they will take the hi-cap versions of the AK47 and M-14 (respectively) mags.
You have to look at the market niche these are aimed at. I'm not too interested in the 7.62x39 rifle, but if someone wanted a hi-cap rifle in that caliber in a state where the commissars had forbidden evil semi-automatics, this could be a good choice. The LE action is very fast. I once shot an IDPA side match with a No4/No5 conversion in .303 and finished in the middle of the pack. Everyone else was shooting semi-autos, mostly in 5.56mm.
I'm interested in the 7.62x51. I've always wanted one, though I'd have to immediately start chopping on it. They are heavy. I'm not sure if it is a heavy barrel, extra metal in the receiver or if the wood is really dense. The ones I handled were very nicely made. I'd rather see the carbine version with a No5 style stock, but they didn't ask me. Wait, actually they did. I talked to the guy from Tristar 4 years ago and told him what I thought so I guess I should say they asked, but didn't listen.