Great!
I've been trying this out in Bane. Confirmed that I can:
(a) change racial stats (strength, et al.)
(b) change class requirements (again, strength, et al.)
(c) change class skills (e.g., take ninjutsu away from bards and rangers, or add alchemy and theosophy to bishops)
(d) change starting equipmentI can probably change resistances, hit probabilities and mana regeneration, but I haven't tried.
Things that cannot be done (yet?):
(a) spell picks: while there is a field for setting spell picks, changes to it are not saved and seem to have no effect; I'm not sure if this was intended to set starting spell picks or to set spell picks available upon level up, but it does not work either way (for example, I tried to remove spell picks from bards, but they still get them, starting at level 3; I tried to add spell picks to monks, but again, they respond normally: no starting spells and getting theosophy spell picks starting at level 3)
((a1) A side thought: is there a way to set the level at which a class starts learning spells? That way, spell ability could be removed from a class simply by setting that to a very high number, or it could be enhanced for a class by setting it lower.)
(b) musical instruments: musical instruments can still only be played by a bard; making instruments usable by all classes and/or giving all classes music skill has no effect on this (I suspect this is hard-coded to the bard class slot, but I wouldn't know)
(c) merging items: it is not yet possible to create new mergers (e.g., light heal + mod heal = hvy heal) nor to see or edit existing mergers (e.g., rope + hook = rope&hook)
(d) race features and resistance modifiers: these cannot yet be changed (I, for one, don't care much about this; although if we could unlock it, we could really create entirely new races; however, modifying starting attributes is already a good step toward this)
Mind you, NONE of this is a criticism. MG's work is great, and continually opening new horizons to us in all three scenarios. I am just (a) doing some beta testing for the lower versions (since not so many folks bother with them), and (b) voicing my own opinion as to which remaining horizons it would be really great to see next.