It has been over three years since my Walkabout was sold, and my first reaction was "too many knobs".
I do not like the preamp overdrive tone at all when driven hard (gain knob past noon or 1 with high output pickups). But sitting right below it, "on the verge", is excellent.
FWIW, I never cared for the Streamliner preamp driven hard, but I loved it clean. And I rarely pushed the Walkabout gain past about noon.
Aside from my Ashdown, I never heard a 12__7 preamp tube drive that I much liked with bass guitar. I get heavier overdrive mostly from pedals, my favorites being the Bearfoot Blueberry and Mad Professor Blueberry (and rarely for "always on" flavor).
I only had the D-800 for a few months, but for a person doing a lot of wide variety gigging, I could see the benefit of owning both the D and WD.
This is all very encouraging, and aligns with my experience of my Walkabout. I really bought my Scout for the cab more than the head. I tend to run it Gain at 12:00, treble boosted a bit, and otherwise flat as a board, and it sounds great. It was only about two years ago that I ever even began to think about the parametric EQ section (oddly, after checking out the Darkglass EQ section), which I then discovered is capable of a fairly good approximation of the old Trace Elliot Pre-Shape EQ curve.
I don't use overdrive on bass, because I think it sounds weak. But the sound of the preamp tubes *just* edging into the saturation/compression zone is where I think tube amps sound wonderful on bass. Over the years, it took a long time for me to admit that I generally prefer a crystal clear solid-state preamp. This became obvious to me when for a few years, I switched to an SWR Interstellar Overdrive and Power 750 as my main rig. I found I was spending all my time on the solid-state side.
That rig also included a Trace Elliot V-Type rackmount and a JoeMeek VC1Qcs channel strip (for either a full preamp, or just the compressor), so I had two tube choices and two solid-state choices. It was too much to carry, though wonderfully versatile.
These days, I'm using my Walkabout with a Boss BB-1X Bass Driver, and I leave the Walkabout clean and the BB-1X in that magic "just beginning to saturate/compress" zone.
So yeah, I can totally see owning both the WD-800 and the D-800+. In fact, I can see maybe even owning the D-800, as well, *and* having the pedals as a backup.
I don't think I've been this excited about an amp release in 15-20 years. When I am finally able to purchase, I have a feeling this will be the last rig of my life.