Hi Jeff,
I do hope that you find the Swirl Killer as much of an upgrade as I did when my very old polisher died a couple of years ago and I purchased the 15mm and shortly thereafter the 12mm. I never had any complaints about my old polisher, but that was only because I didn't know what I was missing compared to the Swirl Killer.
The speed in which I could do a vehicle was cut by about 15% just because I didn't have to stop as often due to the heat on the old polisher. The other thing that I noticed was that my arms didn't feel like jelly after a couple hours of use with the old one.
Best of luck with the new toy and the 30% off is an excellent deal also.