I made use of them all the time with rubber dome keyboards, they lay usually pretty flat on the desktop. In the case of the Sun Type 7 I used the middle raisers, a full raising was a bit too much.
With my Model M I didn't felt it was really that necessary until I tried it on my own desk (the keyboard had to travel around until I got it to my place) - the sound of the keyboard changed drastically. Since the desk is rather big and with a lot of space underneath it boosts a bit the noises you produce on the desktop, but with the raisers on the sound just feels clearer and crispier.
The height seems to be OK, but I'd like to have it like this for one more week to see if it's really better position wise.