Just bought this and decided to try it out after a day out in the sun, accompanied by my son and a cheap variable ND filter.
I shot slow-motion in V-Log, 4K24p in HLG, and when I switched modes to shoot some stills, I forgot to switch back to HLG and later realized I had been shooting half of my video clips in the Like 709 profile.
When it was time to learn the workflow of these LUTs, I tried using the Joo.works GH5 colour correction kit (which turns a few of the other profiles like CineD into V-Log) to prepare the wrong clips, and to my surprise it actually looked pretty good - especially considering the conversion was from Like 709, which wasn't right at all.
Disclaimer: My colour vision is not the best, but this might be useful if you have some old CineD footage you have laying around that you need to spice up! Although I hopefull won't make the same mistake again