I've never owned a Grand Design, they were a new company when the wife and I purchased our 5th and were not sure we wanted to go with a new company.
Now we've meet lots of Grand Design owners and every single one of them is happy with their camper. I've talked to full timers, part timers, and weekend warriors. They all love the sales experience, service, and most have gone and done the factory tour and said its very different from other camper manufactures.
If i was in the market for a new camper, I'd give serious consideration to Grand Design.