I actually find that LOTS of recordings donplay back exactly at A440. Mainly things from the 70s and 80s like AC(DC or even Steely Dan are typically close to 1/4 tone flat. Maybe the tuned flat but more likely the discrepancy crept in transfering between analog reel to reel tape machines.
I can’t personally see any need for a less than semi tone transpose for live use or studio use but can see the benefit of quickly retuning to a track for play along practice and transcribing parts. However, I avoid having to retune the guitar to each track by using a simple playback app with a tuning festure. I use Transcribe! By Seventh String which makes practice a breeze including tuning, slow down, loop section etc. For me something like that is much more useful and valuable than using the Kemper to retune to the track. Also, unless playing relatively loud the background dissonance from the acoustic noise of the strings along with the Kemper sound drives me mad.