I've not noticed any line shyness from Crappie and like you said, many if not most people use Hi-vis line. I use 4# about 80% and 6# the other 20%. That said, I'd guess rare is the (Crappie) lake with water that clear. Only water I fish that clear is some of the WNC mountain lakes and I'm fishing there for trout anyway, not crappie, so I have no first hand experience to help you with.
One way to find out! Spool up one reel with hi-vis and use one with your regular clear mono and compare for a few trips. If strike ratio clearly proves less with the hi-vis you'll have your answer.