We did a race on Touhou 15 : LoLK when it came out.
Since it was a special run to end a full Touhou Marathon stream, we split into two team (one really good player ~ can 1cc most of the game in lunatic and 3 okay-ish player ~ can 1cc some game on normal).
It was our first playthrough so we went in point device mode, lunatic for the 1-man team, normal for the 3-man team, we switched player at every life lost and it was pretty tight until Clownpiece.
It was something really fun, but i'm not sure that it could still be feasible since that most of the players now know the boss patterns. (well, it's still doable, but the fun part was trying to find out how boss patterns worked, now it would be only skills but it's not a bad thing either)
Doing a pure speedrun wouldn't even be pleasant to watch since you probably won't be using most of the game mechanics except bombs (no crazy graze milking points and stuff).
Instead of a speedrun, a pacific run would be more interesting i think.