I was fooling around with my D-800 last night and despite all my other SW amps having more features (except the D-350) I found it still to be surprisingly satisfying.
The controls are simple and straightforward and the EQ points for everything are well-chosen. While the other SW heads are a little more inherently brighter/more open sounding to start, this head doesn't sound muffled or inarticulate. It seems slightly warmer/darker in comparison to the other SW heads, but that is simply "its neutral starting point"... not all that you can get out of it by a long shot.
IME the trick with the D-800 is to use the voicing control to get the head sounding essentially like what you want, especially in the top end (you have 3 EQ controls and deep switch to rework mids and bass). You can then use the EQ controls in combinations to bring back some mids, dial back the deep bass, fine tune the treble/upper register, etc. Remember too that it's okay to switch in the deep filter and then dial back the bass EQ. When you do that the lower mid control can become very helpful in shaping a lot of what we hear as the sound. of the bass.
The reason this works really well and the overall tone stays balanced is that the voicing control is not a simple mid frequency scoop/high & low boost, there's a bit more going on. To complement that, the EQ control center points and Q's are designed to work seamlessly and musically with the voicing control. The fixed internal HPF is designed to be effective yet unintrusive.
The other thing about the controls is that they offer a lot of range throughout their rotation so you can sculpt the sound almost surgically once you have the vocing baseline set.
I hope some of that is helpful as you're deciding what to do. I use most all the SW heads and the D-800 still impresses me every time I play it. Good luck with your decision!