I'm confused

Leblanc uses a 10 x 7 prop and I've heard people using 11 x 4.7 props on 3d planes, on the A 30-28S. But from what I read in the north east sailplane products is that max prop size is like 10 x 5... here
http://nesail.com/detail.php?productID=3550
I was also wondering if I could use this power system in planes I mentioned above (mini edge, PA Katana etc...)
I will get the mobius, the only thing is that I'm 14 and I have to talk to my parents and etc...
Paul