[cable_guy]

 Whitelisting has appeared in Kodi Leia builds.  This allows you to select which resolutions and frame rates Kodi will use. If you select 720p and 1080p modes at the frame rates you want - then 720p will be output in 720p, 1080p in 1080p and 2160p at 2160p, leaving your UHD TV to do 720p and 1080p to 2160p upscaling, not Kodi.

NB the approach Kodi devs have taken to whitelisting isn't 100% popular (it's reduce the ease of config of auto refresh rate switching) - and so I wouldn't be surprised if a change to the configuration of the functionality took place, however I expect the functionality itself is likely to continue.   

 thanks. Sounds like a good compromise to me. Although I don't quite know how "ease of config of auto refresh rate switching" would affect me.  

Do most tend to install clean Kodi or SPMC on it?   

SPMC is deprecated now I think - since its dev joined MrMC's team?  (Think MrMC is still very Krypton)

I'm running a Kodi Leia nightly from a week or so ago. 

I guess Krypton has the upscaling quality issue then? (As I presume the whitelist of resolutions isn't available in the older Krypton)