We have a discord server for anyone interested: https://discord.gg/Kh4T3Nb
I didn't even know forum entries were a thing, so sorry for the late reply. Co-Op runs actually wouldn't be any faster, I think. Mainly because of the added lag and bosses still having invincibility frames, which means only 1 person can hit them at a time anyways. Only timesave compare to 1p runs would be the final boss with p1 standing at the head and p2 hitting the body.
Additionally the camera has to be manipulated, so the screen scrolls faster, which might actually work out better with 2 players. Would need some testing for sure. It might actually be fairly interesting (at least to me) to see someone attempt it. That said, no one attempted it yet. There were some people who wanted to see a 1 player, 2 controllers run of this. But as it is, it's not a really well known game anyways.