I rode a Husaberg 501 several years back, a friend was sponsored by a local shop and they gave him a 501 to see what he thought about it. Anyways, to me it felt very similar to my 99 KX 500. I will say that I think the KX 500 still has a bit more acceleration. The Husaberg didn't feel as responsive. This was the first 4 stroke I had ever ridden. I'd ride one again, I did like it but like my KX better.