I don't use the CPU clamping, but the CPU Priority helps keep most users working most of the time once it's tuned and certain processes are excluded. Users notice when it's not working.
Memory doesn't help all that much but frees up a bit by pushing to the pagefile. Don't want it to be too aggressive for sure or it ends up thrashing. Again, though, users notice when it's not working on the servers that are being pushed to limits.