The key with LED is do your homework. LED' inherently put our a high, UV and low red spectrum. You can have a LED bulb with a CRI 80 but anything red under it is gray or black. The LED's can be doped to fix that however that coating will be bombard by the UV so then it will come done to the quality of the doping. Rules of thumb for lighting do not apply to LED lighting. Rules of thumb from one LED light does not necessary apply to another LED.
Retrofitting of existing lights can be trickier. LED' can operate at varying temperatures however They are not tested in every type of light fixture out there so they are listed as "Classified", not "listed". It means it's listed per say providing you install and use it within the designed parameters however they do not know how it will work in your setup and if it fails, it's on you, not them, thank you for your business...
Do the research, use reputable brands, don't buy the sales pitch, don't buy the box, buy what's inside the box. When retro fitting, do a few and wait. SE how they perform. When buying LED's for a larger area. Buy at least enough to finish an entire area or room, don't stop in the middles. Get educated on LED and lighting design.
"Live Awesome!" - Kevin Carosa