Re: What schmidt and bender??? is better
I could be mistaken, but I don't think parallax really begins to be a concern until you get above 10x.
If SB had any concerns at 12x, I'm sure it would be included on that model.
If you're strongly considering ART for either one, then call Darrel Holland and ask him what he thinks. He's very technical as well as practical/experienced and will be happy to answer your questions.