I don't know if it is normal.I have seen the same speed as you. 20 downhill on blacktop. It is not an issue for the wife and I, we purchased it for dragging trees and hauling rocks. When it is loaded and going uphill it is very slow. But it has pulled everything we have put on it, probably to the point of abuse. We looked at the 900s, but the diesel goes for a long time on a tank of fuel. I have no qualms about recommending the Brutus for a work vehicle. I don't have to start and drive our GMC diesel just to drag trees or haul rocks or whatever. I do have a 500 atv to chase cows on occasion, or carry a sprayer for thistles. I can't see us trying to stay up with my sisters when they go trail riding with the Brutus, but I don't think their Ranger or Razor will do the things we do every day.
Just my opinion.
Just my opinion.