Thor is a holding company that owns several RV manufacturers. Dutchman is one of their operating companies, as is Keystone, Airstream, Damon, Chateau, Skamper and others. Dutchman is focused on great value,which translates to lots of eye candy at a low price.
The address and phone number for Grand Junction is the same as for the Dutchman Company, so I assume it is still being manufactured in a Dutchmen plant by Dutchman employees and under Dutchman management.
I have no data that says there is anything wrong with a Grand junction, but experience suggests to me that a Chevy in fancy trim is not in any sense a Cadillac, if you get my drift. You might make the same argument about the Cardinal because Forest River has low end models as well as mid and higher ones. I think that Forest River has more lines with higher quality images than Dutchman, but it's all subjective.
Don't let me scare you off if you really like the Grand Junction. But if the Grand Junction appears to be giving you a lot more stuff for a lower price, you should wonder what they left out to pay for the other stuff you are getting, cause there is no free lunch. If the price and features are comparable, then this is not a concern.