Personally, I'm (mostly) only buying 4Ks of films I don't already have in any HD format unless it's proven to have a far superior transfer or it's a firm favourite of mine. I just couldn't afford to get all of the new 4Ks coming out, especially now as they are gaining momentum and more and more it's a UHD of a film which has very recently had a new remastered bluray which already looks perfectly fine.
Believe it or not I hadn't ever seen Dog Soldiers previously (I had mistaken it for the
Jamie Bell Doomwatch film) and it does look fantastic. Sometimes though the difference between BD and the UHD is minimal and at least £10 dearer! Even more with this current trend of a hard box and 60 page booklet, poster and art cards which you look at the day you buy and then never again
That being said though, there are some bloody good looking UHDs out there, Jaws for example!