Popriv,
Yes, the hatch method of servo mounting is used in a lot of ARF's, but there are plenty of kits that use that method as well. Sig Hog Bipe is the one that jumps out in my mind immediately, but if I think about it a bit I could list more of them. This method of mouting the servo is more than enough to hold the servo secure. If you would like to make it a bit more secure you can have the hatch screw into the spar and the trailing edge of the wing, which will give it a bit more strength than screwing it into the rib mounts.

Ken