XMT#2 is like #1 on 'roids. It's very good at removing minor swirls. You just have to let it work and use a lower speed like #5 on your PC. I get no dusting or pad clogging with it.
Optimum's Polish is very good as well. It's more pad dependant than anything. You use a tough polishing pad, swirls will disappear. Use a lighter pad for a more refined finish. No dusting with it either. There is a little more work since the PC takes longer to build heat and Optimums products are heat triggered.
It all comes down to preference. If I was buying just ONE line, it would be the DP line. The polishes are tough and do their job. Since they are not as good in the sun, I'd get the XMT line to go with them. You can get all of the DP stuff on sale now for 9.99. That's a stupid insane deal for such a good product.
BTW, I will be doing a complete DP detail at Detail Fest 07.
