Is 4sevens making top shelf quality lights ---- No. But they are making a solid mid-range quality light at a good price, and with a 10 year warranty. I think 4sevens is getting a lot of things right. They value several things that other companies do not value as much. 4sevens places a high value on keeping their lights small, compact, lightweight, powerful, and versatile. The quarks are smaller than most of their competitors and more lightweight. They place a lot of value on keeping up with technology (latest LED.) They also place a lot of value on their lights being versatile, and this subject is broad regarding the quarks:
They're lego-able with each other (tail, body, & head.) You can convert your Quark 2xAA into a single AA light, or a single CR123 light, or an 18650 light (this body no longer sold,) or a single 17670 light (using the 2x123 body.) You can even use one of the turbo heads in any of these configurations with the right battery. There are multiple tail switches to choose from and a deep carry pocket clip that you can get, plus other accessories. They're designed to use every type of battery chemistry (alkaline, lithium primary, NiMH, & Li-ion.) The circuitry can handle each of these batteries because they are using a buck/boost circuit in the quark line. They have two UI's to choose from. The quarks with the tactical UI are programmable. There are not many lights in this price range that are programmable. The output options are very versatile as well offering a really low low to a very bright max. The output options include - moonlight, low, medium, high, max, plus sos, strobe, and beacon.
With these features I can't think of a another brand out there that's doing all of these things with their lights in this price range. In fact, there aren't many higher priced/quality lights out there that are doing very many of these things. 4sevens has a pretty good niche with what they are doing which is why they are popular & well-liked by many around here. They could get upstaged by other companies, but at the moment they're doing a pretty good job & providing us with good lights at a price many of us are willing to pay.