It's not that I think a donkey would make a fine pack animal, a donkey IS a fine pack animal and has been so for thousands of years. There's nothing like the sound of horses and the smell of fresh brewed coffee in hunting camp as the sun slowly creeps in the east.
Burn the quads.
PS: I edited this after reading the title of the original post. I think that riding the donkey could be a tad uncomfortable. They have a short but quick stride. Finding a comfortable saddle that fits "the donkey" could be a problem, your cahonies might get an overhaul. A mule is a much better ride. PS those that think mules and donkeys are stubborn are not well educated on the topic. They appear more stubborn merely because they are in fact smarter than horses. Mules and donkeys won't get themselves into the same predicament that a horse might. Anyways, you can still burn the quads, hey but that's just me...don't take it 2 seriusly.