Running it at 1 would be recommended I think. IIRC I leave mine just over 1 (like 1.2 or so)
Before I knew better I ran the Dewalt at full speed (oops). Admittedly, I don’t see much difference in the cut quality between the 2, but lower RPM has to be a lot easier on the router I’d think.
Also, don’t slow down the speed of the cut too much if at all, If you go too slow and are not clearing enough material the bit will get hot or burn up. I think you can run the machine as fast as possible and not have a problem, its the depth of cut and the rigidity of the machine that will cause chatter, in my experience.