I recently installed the non keymod UTG pro super slim 15", very easy to install, lined up perfectly with my upper and locks up solid. Overall I'd say the quality is VERY good, the barrel nut design is nice in that you don't have to index for the gas tube, just the large slots so that the insert that the rail bolts to lines up. On mine I had to torque to 45ftlb for the slots to align correctly allowing all 3 sets of mounting bolts to align with the insert, no barrel shim needed. The included barrel nut wrench is not bad at all, I've seen some say that it's "soft" but I didn't see that in mine... worked perfectly and I torqued and re-torqued mine 4 times before settling on 45ftlb's when everything lined up correctly.
If I had to say anything bad it would be the that the screws have that HARD blue thread locker pre applied and the included 3mm allen wrench seems like the typical poor quality type, it may not be but I use my Proto 3mm allen anyway, as for the thread locker I just used my dremel with a soft wire wheel to buff off the blue crap and then used regular blue Loc-tite.
If weight matters... my 15" rail with barrel nut, screws and all 3 rail sections came in at 14.5oz. My mid length HG's and barrel nut W/delta ring came in at 11.5oz. . now I didn't have a low pro GB... I shaved my standard FSB. The top portion I cut off was nearly 2oz!!! add in the bayonet lug, sling mount and the clean up grinding I'll bet I took off 2.5-3.0oz off total. in other words... the rail didn't add or remove any weight for me, I do like the THIN profile, feels good in the hand.
All in all I'm pleased with the Rail, good quality and the price point is nice, the only thing I'm not sure of is how well the finish will hold up... time will tell but I'd buy another
John