There's also a subdungeon that looks more or less like the old Mothers for Safer Dungeons or whatever, with a couple of gold piles and a sign - except if you actually bother to read the sign (which I rarely do, so I have no idea how long this particular subdungeon has been there) it has a somewhat poetic message about heroes and helmets (or something like that). There were also a few walls in one of the corner that I had no means of interacting with, so it's possible there's some goodies to be had.
On the topic of HALPMEH - I would just note that changing it to 4 MP and 4 HP * level would have one very, very major unbalancing effect. A Wizard with Mana Leak and a Crystal Ball would still have an effective 1 MP HALPMEH, only now it heals 33% more HP than before. Add BLUDTOPOWA and he'd get a patently ridiculous 80 HP per tile.