What changed because of them
Marks holds a PhD in Electrical Engineering from UIUC and publishes in computational imaging and radar. On GitHub he keeps more than seventy open-hardware projects: a VNA, an antenna tuner, a Nixie clock, a Z80 computer, and among them a whole DRSSTC PCB pack.
UD2.9, released on 15 May 2018, is loneoceans' UD2.7C rebuilt through-hole, easier to hand-solder and easier to source, with a pulse-skip jumper added. It came six weeks after UD3 and is a different branch entirely. Eight years later Mads Barnkob built Kaizer DRSSTC VII on it unmodified, and WaskaLabs continued the through-hole line as UD29X.
Their boards
UD2.9 
schematic: UD2.9 Skip Pulse, drafted by Daniel Marks (KiCad, 28 Feb 2018)
Builds and boards on the tree
- UD2.9 · 15 May 2018
- Kaizer DRSSTC VII, running UD2.9 · 2026
Sources
Written from what Daniel Marks published, by one person, so it can be wrong in places. The page is meant to become editable, wiki-style, by profiles above a trust level. Until then, corrections go to the forum, and anything Daniel Marks asks to change or remove is changed the same day.