They have a tread more effective than a knobby, but smooth is definitely better on the playa.
I might shave a surly tire, if possible.
They are expensive, but I have ridden one on the playa enough to be impressed.
I have ridden the Endomorph on the playa.
I think it is adequate for a normal rider on a non-electric during any playa conditions.
More weight or worse surfaces might make the larger tire a good idea.
I will probably do the front wheel conversion first, when I can.
For 65 mm rims
100 mm rims - Big Larry
I would shave these for sure