I purchased a Mallard IDM29 last summer when the 2017 came out. Grand Design was not in our area at the time or we would have considered it. My folks just bought a GD in a different floorplan and it is really nice.
The listed dry weight is around 5800lbs for the Mallard, but as delivered, mine was 6400lbs. Like someone said, be sure to check the sticker on the unit itself.
The poster that mentioned the proximity of the foot of the bed to the wall is right. That is our one gripe of our Mallard. I do like that the TV swivels so we can watch TV after the kiddos go to bed.
One of the things we considered was storage space when we compared different brands. The Mallard has enough storage for our needs.
I tow our Mallard (and the folks' GD) with a 2003 3/4 ton Suburban. It struggled a bit going over the mountain passes (which were 80 degrees at the time!) last year, but I made some improvements over the winter (bigger aux trans cooler, Black Bear tune, Power Stop brakes, Sumo Springs) and it did fine on our first trip this season.
One thing I will mention is the Mallard prefers to be front heavy. It took me a couple trips to balance our load to reduce bucking. One thing that threw me off was we have our bikes on a rack hanging of the back bumper of the Mallard. With the rack and four bikes, I bet that is 250 pounds easy.
As far as pricing, remember, RVs have HUGE markups. Our Mallard's sticker price was just under $30k. We paid $21k. Enjoy!
Just took a look at the GD2800H. Nice! A couple notes. I like how the bunk can raise up and make room for storage. The outdoor kitchen is nice as well. One thing that drew us to the Mallard was the direct entry to the rear bath. It's nice if you are at the beach or it's rainy out and you can usher the kids right to the bathroom and not track slop through the trailer. I like the ladder for the bunks as well. Ours did not come with one.