On typical single-track with bumps and roots it is a lot rougher than a suspension fork. But some find the challenge a bit more interesting.
You are going to notice the lack of suspension way more than the loss of weight.
I went through a rigid phase in the late 2000s as a way to spice up some of the smoother trails I was riding. That’s also when I was dabbling in single speed. But I also had a geared FS bike at the time.
Both were intetesting, but after the novelty wore off, I went back to suspension and gears.
The only mtb I run rigid now is my fat bike.
As far as the fork length, you generally go a little shorter when going rigid, because the fork does not sag or dive under braking.
Last edited by Kapusta; 11-15-22 at 11:50 AM.