Good deal, man. We actually ended up buying a 2400BH new in TN. Wife and I made a LONG first trip through the Smokey's, Shenandoah, etc to get home. 9 hour drive. We ended up with a low end EAZ WD and anti-sway hitch. I thought we were getting an equalizer, that's what they sort of sold us on, but wasn't worth the argument at that point over a couple hundred dollar difference. It worked fine on the way home once I got it dialed in. Towed like a dream. Make sure to stay in 4 and move to 3 if you need to go up a large hill.Dewstain - didn't see your post which would have helped me a bunch! About a month ago, I went through a two-week process of buying and configuring both a 2015 QX80 tow vehicle with 123,000 miles on it as well as a Grand Design Imagine XLS 23BHE (slightly shorter and lighter than your 2800BH).
In case anyone hasn't seen,here's a good video on setting up the QX80 brake controller connection with this pigtail adapter from Amazon.
I too went with the Tekonsha P3 and really liked the ease of use while driving. Saved a newby like me from some interstate jitters once I realized how effectively and dynamically it worked in applying predictable levels of braking on the trailer.
The dealer threw in the chain-style WDH with bolt-on friction sway brake, which I took on a 300 mile round trip through the Ozarks. Once I really clamped down the pressure on the sway brake, I had zero scares despite traversing some pretty hilly, wind-exposed and WINDY areas at 60-70 MPH. Knowing that I could reach down and gently blip the Tekonsha brake any time I had bad wind effects was enough - almost never had to use it. I do plan to upgrade, and after doing some research, the Husky Centerline 800-1200 pound spring bar style will be my next purchase - it's a bolt-on unit, so no drilling on the trailer A-frame, and gets reviews right in line with the $500+ hitches from Equalizer and others.
My one caution would be that the Grand Design trailers are light on the tongue weight, I guess to give you more TV GVW capacity when you actually load the pass-through compartment on the trailer.
Your trailer looks to be about 5700 UVW with only 505 pounds on the tongue, well below 10% which is the bare minimum and way short of the recommended 12%+. Driving the trailer home from the dealer on the interstate and running with only UVW on the trailer and with a very low setting on the sway brake almost had me turning around to drop the trailer back off at the dealer. Once we loaded up 200-300 pounds, almost all to the front of our trailer, and clamping down the sway brake, driving was almost enjoyable.