This is kinda IPS vs PLS. The overlord is an IPS panel and does not suffer so much from side effects when overclocking. The Qnix is PLS and does have gamma shift after overclocking. The IPS panel generally has a bit better cool colors and will have a cooler color hue to it. Where as the Qnix will have a bit more of a warm color hue and better blacks/darks.
The fact is that both panels for accurate colors will need some calibration. The difference is with the Qnix you will need two(or more) color calibration sets(one for each frequency ie 60hz vs 96hz vs 120hz) where as the overlord(IPS) will only need one(as there is not really any side effects). Many have been able to calibrate manually, using posted color profiles or with a pro color calibrator and been perfectly happy with the Qnix results. On the other hand the Overlord has posted color profiles that many have been able to set and forget.
ANY panel can have backlight bleed issues. The overlord panels due seem to have a bit better track record on BLB. But on the other hand there is a pretty easy and tutorial method for fixing BLB on the Qnix(this is because there is no BLB, there is panel pressure from the crappy bezel that causes bright spots). This does involve opening the case though. I would say overlords has a better bezel since it doesn't natively cause pressure and thus bleed but honestly i think both monitor bezels look bad. This is why i debezel but not all want to.
For overclocking they both have a pretty good 96hz OC track record. The 120hz probability is a bit harder to spot since the Qnix seems to have a bigger member base who report. I would say if you follow my monitor overclock timings method in teh Qnix forum there is no reason you can't at least get over 100hz with either panel. If you look at ToastyX and the catleap forums there is a wealth of tips and tricks for getting 120hz and for the Qnix possibly higher.
I have owned both IPS and PLS. I have had experience overclocking both as well. As i previously stated the IPS did not have any visible side effects where as the PLS NEEDED calibration. After calibrating though there where no issues i could find(especially with timings optimization). I would say for editing or anything based around development IPS takes the cake just by being better at a more natural look and seemingly more accurate colors. For gaming, movies and really anything entertainment based PLS was just better and nicer to look at. The vibrancy and saturation is awesome.
Overall there is a IPS vs PLS decision for you to make regarding your choice. Then there is a piece of mind factor. This is because the overlord model or IPS variant is more overclock friendly(with colors) and doesn't have a very probable BLB through panel pressure. The Qnix just has a bit of "some assembly required" with it. This is however off set by price. Excluding the IPS/PLS fact the overlord higher price is justified by its ease of use.
Bottom line is PLS vs IPS and higher price for ease of use/mind vs lower price with some work. For your use being gaming and entertainment i would recommend the Qnix unless you don't want to any quality improvement(or very little). I also recommend doing lots of reading in each panels corresponding threads for even more in depth info(there is always more info
Hope this helps