I've had nothing but Samsung TVs and never had a problem, except for an old DLP that would randomly shut off. A firmware update fixed that though. Anyways, I'll take refresh rate over resolution (assuming those 4k sets are only 60Hz at that price). Also, I don't think anything plays at that resolution anyways. Cable broadcasts in mostly 720p (some channels at 1080i) and blu-ray plays at 1080p. Future blu-rays are going to try pushing 4k though, so there's that. My point is unless you hook up a crazy gaming computer to your TV, it's wasted pixels at a low refresh rate with a high price tag.. for now. By the time 4k is the norm, it'll be time for a new TV anyways.
This goes into far more detail why 4k is stupid:
http://www.cnet.com/news/why-ultra-hd-4k-tvs-are-still-stupid/