Security22 - The Ground Pounder does have a few issues but most are easy to deal with.
The first issue you encountered with the wheels falling off is not uncommon regardless of the brand. It has been my practice for the last 20 yrs or so to use light duty blue Loctite on just about everything.
As for the spur gear stripping. That was/is an issue with the stock trucks. The motor mount and gear box are separate on these trucks and they flex independent of each other. It doesn't matter how many times you trade in the truck, the next one will do the same thing until you fix it. The good news is that crawford performance make a MOD1 spur gear for this truck that will never strip. It cost about $15 but it's well owrth it. If you're handy you can make the traxxas Jato spur fit as well.
The other problem you haven't run into yet is the axles. You will break them plain and simple so I recommend that you buy a couple of replacement housings or buy the aftermarket axles braces.
The GP is a fun truck after you spend a little time on it to make it right.