Relatively new user here as well and I personally own the z plus. I like it a lot, but the biggest drawback I have with the z plus is z travel. When I am using a small endmill, I cannot reach the top of my wasteboard. I have a 3/4 mdf board on top of the already supplied mdf baseboard. I’m actually considering stacking yet another 3/4 on top to eliminate this issue. That would be the main reason I would consider the HDZ over the z plus at the moment. If you’re also considering milking a lot of metal on it then I would probably go to the HDZ just to ensure you have a pleasant experience. I have not cut metal with mine yet so I can’t speak for how well the z plus will do in metal.