Hi Frederick,
I recently retired and we are now full time in a Grand Design Solitude 379FL. I cannot speak to the Dutchmen brand, as I have only seen units at an RV show.
The quality of GD appears to be very good. I have had direct contact on a number of occasions with Scott Brouse with GD, who works in a management capacity of some sort on the shop floor. We met at the Austin RV show, and he spent at least 4 hours with us ensuring that we understood all aspects of the design, construction, warranty, etc. Was very honest and frank, which was refreshing - definitely not a sales type person. He helped prioritize our unit through production, so that it was delivered just in time for our transitional needs.
My understanding is that the owners are very accessible to their customers. They are the former founders and owners of Keystone (largest RV mfg I believe), and leveraged their experiences there into the design of the GD models. They left the new owners of Keystone as soon as contractually able, dismayed at the decline in quality under the new ownership.
By all accounts their customer service is outstanding, but after one month we have not had a single issue. I did just notice that the USB charging station (a 12 volt cigarette style plug plus 2 USB ports specifically for charging your other devices) is not apparently working. Will look into this, time permitting.
I encourage you to go to the GD website at www.granddesignrv.com and the owners forum at http://www.granddesignowners.com/forum/forum.php
Considering many people only post about problems, I think you will be encouraged by the tone of the owners forum. For what it is worth, we purchased from Crestview RV in Buda, TX. This was a great experience and I spent 3 days living in the RV at the dealership's RV park (for no charge) after purchase to ensure that all was well. It was.
With respect to the warranty issues raised:
Yes, the warranty remains valid for full timers. You do not have to return to the dealer that you purchased the unit from, but Mr. Brouse was frank when he told us that one would probably get higher priority at the initial dealership. One thing that I liked was that GD is a one stop warranty point, so no matter what fails on the RV they take care of it promptly without having to deal with other manufacturers.
Obviously my experience has been a good one so far. Good luck on your RV and congratulations on retirement. I thought I would be bored, but I most definitely am not!
Tom