Really neet build, build video, and flight. I've only ever seen one other in the flesh and it wasn't nearly as nice as yours. I can see it's a difficult build.
Just a couple of nits on terminology that take nothing from your build:
- 'directional fins' are elevons.
- 'directional fin guides' are actually elevon locks; they prevent motion of the elevons prior to staging.
- 'directional fin actuators' are actually dynamic dampers; the damper is on the elevon and the part on the main fin is just an aerodynamic shroud for the damper - they are separate unconnected pieces, though the gap between them is small. The actuators are in the rocket body at the elevon root forward edge.
Since this thread reveals that there are quite a few that people have this in their build pile, I wonder if they might be interested in a better depiction of the interstage 4:1 shroud. I haven't seen a kit yet that's really gotten it right (tho I doubt I've seen all kits). The real shroud is fabricated from four pieces of flat sheet metal, each 1/4 of the shroud, joined by four triangular pieces of sheet metal that have a single vertical bend. It wouldn't be hard to work it up, and I don't think it would be difficult to integrate it into this kit. Gonna give it a think.