I have the LWRCI DI M6. EuroOptic sold it under then name "economy" but I think it is a discovery. It has LWRC's proprietary handgaurd.
I have been impressed with the overall gun. I'll compare it to a Daniel Defense rifle but for less $$.
A buddy has a LWRC that he put together after trading into a few parts. Hes a lefty and bought the ambi. The difference between the discovery and the full ambi is that obviously, it's not full ambi. The only other difference is that the ambi has a spacer behind the trigger to take up any slop between the receiver set. The triggers feel exactly the same and the uppers are basically the same except for laser etching as far as I can tell.
The guns are light, handy, and they shoot well. Ive shot them side by side 2 DD's, they don't shoot as well as the DD's but they aren't far behind either, not enough to matter. It's simply that "technically" the DD's turn in a tighter 100yd group, but going round for round out to about 700yds, the hit count was the same as long as the shooter can deliver the goods.
If you grt the proprietary handgaurd, you can force MLOK onto it. Specifically slate black industries, the 2 hole panels line up exactly with the holes on the handgaurd but the 3 hole panels do not line up clean, and the vertical grips and barrier stops will bolt up as well. You can make the MLOK nuts work too but there's some slop and personally I don't like how it feels. The MLOK screws are not the same thread pitch as the LWRC mounting holes either, you'll have to scavenge from your parts or go by some. Edit: just looked and the screws are counter sunk style 8-32 with a T20 head, look to be 1/4" or so but most of what I've uses so far has been 3/8" and 1/2" for some applications.
Last is to torque the handgaurd screws immediately once you get the gun. I haven't had a problem, but I noticed they weren't all tight, 50% were good, the other got a fresh application of thread locker and a torque to 15inlbs. They are short screws with not alot of thread engagement so if you go too ham on them they'll strip out.
If you want to put ARCA rail on, Area 419 Universal 4" will mount up well for use on a tripod