If they let us heal between gates on 1F, I'd be okay with that.
either that or:
make the monsters hit for less damage
make the monsters attack slower
reduce monster count
gain 1sec invincebility upon hit (like everywhere else)
that would be my suggestions.
As many others mentioned before, clearing B1 is already kind of hard.. it really frustrated me to finally finish B1 and then get stuck on the last stage :c