I have the Wolf dual fuel 6 burner range with grill & double ovens. I think I've chatted with you before Twinglemum! We have natural gas though, so I can't answer your questions on LP (propane). We did use a propane tank for a basement heater in our old house, and it was very expensive to refill the tank.
The range is like a piece of art in the kitchen - and like the OP said, I've never had 5 or more burners in use at once. I have had both ovens going, but rarely. The grill is nice in the winter when it's too cold to grill outside here. But is IS messy to clean up!
If I were to remodel or build I don't know that I'd go with the Wolf again. Not Wolf specifically, just a range that large. I love it - no complaints - but it cost more than my 1st car, and I think next time I'd use that money towards something else.