Well if your using the 3M Swirl Mark Remover and if it is not working too well maybe you can just change your method of application to possibly get different results. I was a little worried myself but I heard from someone a while back that the pressure from the Porter Cable is not going to hurt your paint, it'll just help make the product (SMR) work more efficent. I'm not saying strap a 25 pound weight to the Porter Cable and bash it around, all in good judgement.
I apply the product to the pad or the panel and I get my Porter Cable up to speed 4 to 4.5, I move it at the rate of about one inch per one second for the first pass with pressure, I make the motor work... on my second pass, I move about two inches per second with half of the pressure of the first pass, I do the same for the 3rd pass and on the 4th the motor is spinning as free as a bird and the product is already hazed, I just wipe off the 3M from there.
When I first started I used to apply hardly any pressure on the Porter Cable and it was a pain, I had to make WAY too many passes and I was causing swirls from the pad going over the surface too many times. The 3M Swirl Mark Remover is a really good product, if you use the right method of application.
Take it easy bro.