We travel the southland almost exclusively, so for the money, the heat strip may be all we need most nights. We did our last trip with a 5" cube space heater sitting on our stovetop, and occasionally got overheated.
If I had had the option to order my rig with a heat pump, I would have, because I had one in our previous rig and loved it.
We expected our rig to come with the built-in fireplace, but it didn't (it came with the swing down stairs instead, which we were going to add anyway). We've toyed with the idea of adding a fireplace, but (aside from the fact that it's more heat than we need most times) I'm not sure if I'd have to cut a fireplace-sized hole in my paneling to install it. On the rear of that paneling is the outdoor grill/fridge hatch, so I'm concerned.
The nice folks at inCommand said that if I added a heat strip, they'd send me a custom floorplan for my unit that included it.