I confess I have never looked at the compass in my glider when I'm flying... Of course XC gliding doesn't happen when the sun isn't visible regardless of if it's thermal or wave. At least I don't go XC without a visible sun, and I find it an invaluable navigational aid. Moving maps are wonderful, but one needs to have prepared enough to manage without should the electrics go down as can happen in a glider since they are all on batteries.