Just beat 8/20 mode on version 0.4.2 and I'm a happy chap. I'm so, SO excited to see where this game is going to be taken from here, especially since the gameplay loop is possibly the most fun FNAF game I've ever played, and that's coming from someone who's played Frickbear's 3... Actually, half of that game is just minesweeper, so fair enough...
I'm going to say that the max mode in this version is around the same difficulty as FNAC 1 custom night '7/20', which isn't that hard honestly. Catti is by far the worst one since she always manages to start sprinting right when you try rebooting a system, which forces you to either wait and do another cycle with Merri and Hoppi, hoping you don't run out of power, or you die. Usually doing another cycle is possible, but you can get unlucky sometimes. If Teddi walks past the glass, before four AM, it's practically game over. It becomes much more difficult to keep her away and you can't feasibly rely on rebooting anything reasonably fast when she just charges your open door like that.
This is getting too long now. My point is, it's a FUCKing awesome game. Thank you very much.
Edit: Right! I forgot to mention another few things. Number one is that Creepi doesn't seem to do anything in this version, even though turning her on says so otherwise. She'll appear in hallways, sometimes behind Bratti and looking at her with the mouse makes her go away, but even if I wanted to, I can't die to her.
The second thing and probably a bit more importantly is that I encountered a figure not of the original eight in the gang in the left hallway. She was white, black and blue with another white figure standing beside her. Though I couldn't make out any more of her since I was hurriedly flipping through the cameras at that time, it would be fun to see if anyone else comes across her. Perhaps I'll try posting a screenshot here in case I find her again, but guaranteed, I'm going to continue playing this game.