Can't resist throwing my $.02 in...

Thick airfoils do create more lift and drag (both induced and parasite), and are structurally stronger than thinner sections. In FS airplanes, the section chose becomes important depending on the mission the airplane is designed to accomplish (as can be seen when comparing an A-10 wing to a 757..)

Since most of our models have power loadings (lb/hp) that are astronomical when compared to FS airplanes, drag is easily overcome by our overpowered engines and is not a practical issue, and I agree with Dick that wing loading and thrust/power are the relevant numbers.... Which is why you can see flying model doghouses, pizza boxes and lawnmowers... Put enough power on just about anything, and it'll fly

Cheers!

Jim