Yes, I'm aware of that! Having done it (even after reading through the reviews), I think the size and fit complaints come largely from people who didn't look carefully at the structure of the wheels and the axles on their luggage, and in the kit, and didn't measure the right distances, and therefore ended up with parts that never were intended to meet the actual specs of their luggage. I'm no mechanical genius, just very precise, and I did look at the photos and descriptions of the various kits available (there are many on Amazon) before I bought.
I can't speak to quality of bearings - for a large suitcase frequently loaded over 50 lbs, my set have been fine.
It's a cheap fix, so I'd still say "go for it" especially if getting to a luggage repairer is too time-consuming/difficult/expensive.