I have hinnys and mules, and also a zedonk and would definitely recommend gelding them. I just got my first hinny gelded at the age of 2 1/2 and what a differance it has made in him. As soon as the others drop they will get gelded too. Mine have always been very easy and nice to be around, nothing like some of the horror stories I have been told, so I really do think it all depends upon the individual mule. When I got my zedonk everyone also told me how horrible they were to work with and train, mine now follows me around like a puppy and is extreamly sweet. He has also attached himself to my 34 yr old Arabian, and is his constant companion. I have mine as "guard animals" and they do a great job at that. Corinne