I keep mine at 100%/default but I would guess if you have an oversized RHP that is more than needed for the enclosure, capping the power outage (percent power) would be a good way to keep it restricted from running at full power and possibly getting the surface temp too hot on the RHP surface?
Neither of my RHPs ever got above 140 degrees at the surface so I don't worry all that much. If your larger one is hitting surface temps of 200 maybe play with the restriction setting and see if you can still get temps you want at a capped power?