I received a PC7424 as a Christmas present 15 years ago. It's still running strong. If I were to buy my first polisher today, I'd either get an XP, or the Griot's.
Yes, Griot's DOES stand behind that guarantee.
For me, if my old-codger PC gives it up, I'd think about an XP, or a Griot's. You can get a little more aggressive with the Flex, but given the way I care for my (and my kids' cars), I don't think that I would need it.
For a "first date" today, the XP is fine, and so is the Griot's. Of course, with Griot's, if you have an issue, you can send it back, and Richard will send you another one.
Either way, you would have to be "Moron Tom" to mess things up with the XP or Griot's. Even a lot of the pro detailers who once used rotary polishers are now saving them for the really tough issues. Dual-action, aka random-orbital polishers have improved, and with the vast array of polishing pads/discs, and polishes available, the options available are endless, compared to when my Porter Cable ended up under the Christmas tree a good while ago.
Don't forget to invest in quality microfiber towels for polish removal...