I use a Trijicon MRO on mine. I have an inexpensive Burris red dot on my other one and it runs fine too. These guns are such natural shooters, than virtually any red-dot will make your groups shrink in size and allow first shot hits out to 300 yards at least. I'm not sure of terminal ballistics over that, and view this as more of a CQB weapon use anyways, so don't really care. the MRO has a BIG field of view, which I really like for these bullpups. Have them on other bullpups as well. I'm also impressed with the Holosun shake to wake feature red dot with larger circle/bigger MOA as well as smaller dot for smaller MOA. These are very fast sights to get on target, reminds me of the Eotech holographic that's so proven in combat.
Good luck, it's a fun process!!