Nyal,
I was a commercial power pilot(actually ATP) when I went for a
glider rating several years ago. I asked if I should go for a private
or commercial. I was told in no uncertain terms that I should go for a
commercial. Why? Only 10 more solo flights with slightly more rigid
standards. The savings? Extra checkride.
It makes NO sense for a commercial anything to add just a private.
For gliders, the 10 extra solo flights is a no-brainer.

Dean Chantiles