Nope, no plans to do any new ScummVM releases.
But I respect your decision. Great work you did so far.
Is the source code available? Indivision ECS support has been added to ADoom 1.4. Since that is open source, I guess someone with the required knowledge could port the Indivision ECS code easily.
The graphics glitch I had was not related to palette changes. It was kind of a "damaged" sprite (random pixels that is) that just appeared on screen and stayed there all the time at a fixed position (in-game and in the ScummVM menus). This happened the first time on my A600 and also with WinUAE. I wasn't able to trigger the bug again, however.
Speed is fine with DotT. Only the intro runs jerky in spots. E.g. in the 2nd scene when the two tentacles come out from behind the tree.
Tried again a couple of times and the bug appeared again. See attached screenshot.