I have used the clear pots, but don't find much difference. The black ones do not allow algae to grow on the inside surface and since the dendrobium roots themselves do not need to photosynthesize, I see no real advantage of the clear pots other than being able to 'see' into the roots system. Clear or solid, in my opinion, is simply a grower's choice.
Place dendrobium keikis and small dendrobiums like the ones I potted in the same light as the mother plant was grown. Dendrobiums enjoy abundant light and do best when grown at 2000 - 2500 footcandles.
Good luck to you.
Cheers,
BD