I've never heard of Thermalright, but I've had Hyper EVOs in 2 different systems, and in my current one just before I replaced it with an H80i. It is a fantastic cooler. I'm getting pretty much the same temps with my H80i as I got with my EVO lol. I recommend those every time someone asks about aftermarket CPU coolers. They perform just as good, sometimes better than coolers that cost twice as much. I had a stable 4.5 Ghz on my old 2500K with temps that never went over 70C.
I carry Thermalright and I've never sold one. So I have gotten no feedback and I can't tell you if they good or not. I also sell the Hyper Evos and those sell well and I've not had any negative feedback from customers buying them for new builds. You might try checking the feedback from people that have bought both models on some of the etailor sites. I wouldn't judge the products quality based on weight or you could just put a brick in there it weighs more. ;^D