I have around 1000 hi res albums out of a music collection of 4000 or so albums. I have done the comparisons quite a few times, as I am constantly on the lookout for hi res replacement versions of my existing 16/44 cd rips.
Most times it seems to be an improvement when I get a hi res. It is true that many hi res releases are remastered so you're not exactly comparing the same thing. The 2014/2015 re master of the Led Zeppelin albums have been great. But yeah my cd rips are from 15 year old cd's.
The recent Sgt Peppers hi res is great. I have an original cd, the 2009 remaster on cd, the 2009 remaster on 24/44 USB and now the 2017 24/96 re-remaster. Each time theres a lift IMHO. Guests at my place generally concur.
I have some modern albums by local bands that I know. I am lucky enough that the guys have given me their studio 24/44 or 24/96 master files which they have mastered the album ready for the 16/44 cd release. And you definitely hear whats lost as the music is down sampled to cd quality. The bass on 24 bit files is so much more tangible as just one aspect that shines.
Also there have been some hi res duds as I have replaced the cd rips. But on the whole the feeling is that there are many more hits than misses. I think good hi res offers great sound. And it's pretty easy to tell on my 172.
I hope to audition the 272 when the NDX2 arrives. My thinking is 272/XPS555 versus 282/HiCap/NDX2 are not that far away in dollars so which way to jump? My suspicion is the NDX2 option will win out so I will have to be careful to avoid confirmational bias. I foresee some robust discussion on the forum.