I love the Raptor SD with Kohler 7000 series. I have logged a number of hours in the seat so far of the 54" model and have had no problems. Sounds like you are dealing with a stand up dealer I would not stress about them or the new mower enjoy you bought a good one. We got ours at Perkins in Exeter , NH they were great to deal with.
My Raptor sd 54 has been great so far and I really like the Kohler engine. The 7000 series are supposed to be an upgrade to a Kohler I have on a John Deere with over 500 hours and it has been a great engine. Enjoy that Hustler. Chief