See, now we have a discussion going.
Based only flying a turbo-prop or piston in the Midwest and Caribbean. I already admitted to being incorrect about painting 20k. Definitely usable to paint in cruise. I've taught/addvocated deviating around green because alot of stuff that paints as green can be bad enough turbulence to pop rivets out of a BE99 or give you a lighting stike in the Metro (thing is a lightning rod), both have happened.
I'm black and white on thunderstorms because even a lowly freight operator has collected and now shared (finally, thanks to ASAP) a lot of data on how to avoid issues and the biggest take away was to take more fuel and not be a cowboy looking for a story to tell. That and changes to how to use the radar. Paint up to find the tops, paint down to check for attenuation, paint 8-12 to find the maximum intensity, and avoid green in the Midwest and Caribbean specifically.
@dasleben just stated awhile ago that green gave him a hard time once...