I've played through the 1.5 version and the 2.0, and I've really been enjoying it. The maps look quite a bit nicer with the various tweaks that have been made, as well as the changes to the enemy and item sprites. I particularly like the brightmaps on the weapons in dark areas, it makes them look very cool.
I was a bit surprised by map50 being split into two maps, was that for technical or gameplay reasons? I think it does work better from a gameplay standpoint being two maps, since it was particularly long before, and this gives it a nice break-point.
I like the changes that have been made to Aemi's weapon set, they feel considerably stronger now and better differentiated from Chapter 1. I did discover that her pistol has a quick-recharge in rapid-fire mode, where if you stop firing just as you hear the beeping, it'll drop down to about 30% charge in about a second and let you keep up a much higher rate of fire. I don't fully understand her super shotgun yet, the secondary fire is a bit difficult for me to fully utilise, and the damage seems a bit inconsistent, but I'm inclined to say that's more due to my not understanding it fully. Her BFG does seem weaker per shot with the primary than Lux or Yaeska, but it does have a much higher rate of fire so their DPS is pretty similar, and it deals with Cacodemon clouds better since you can hit them more before they get pushed around too much.
On map50A, I don't seem to be able to trigger the first secret (megasphere), since the tagged sector is the lava moat, and it's a bit too thin to touch. I've also noticed that the chaingunner sprite tends to turn red for a frame during his pain state. That was present in 1.5 as well, so I figured I'd mention it here since I didn't see it brought up before.
I've got a screenshot of it, it's on Imgur:
https://imgur.com/a/ajy4cHNOn the whole, I've really been enjoying playing this. It's very clear you've put a lot of work into it, and I really appreciate it. Thank you for your dedication.