Something I forgot to comment on a few days ago:
FireLance said:
If you introduce a feat to reduce casting times to a move action (say, at +2), beware the machine spellgunner who can fire off a spell as a standard action, another (at +2) as a move action and a third (at +4) as a free (or swift, if you use MH) action.
Not quite. The rules say something like "limit of one quickened spell, power, or spell-like ability per round", not "one spell as a Free Action per round". In the existing rules, the only feats that quickened things were, obviously, Quicken Spell, Quicken Power, and Quicken Spell-Like Ability, which reduced them to a Free Action, but that doesn't HAVE to be the case. If I add feats that reduce casting time to an MEA, it's still fine as long as I clarify that these are still "quickened spells".
So, let's say I add:
MINOR QUICKEN (Metamagic)
A spell with casting time of "1 action" can be cast as a Move-Equivalent Action (this overrides the casting time increase of spontaneous casters). This counts as a quickened spell, counting towards the usual limit of 1 per round. This uses a spell slot 2 levels higher than the original spell.
Someone with this could still cast two spells in a round, one as a Standard Action and one as a MEA, OR they could do a Partial Attack plus a spell. But, they wouldn't be able to do the 3-spell thing you described.
On the other hand, someone with the bigger Quicken feat would have more options:
Partial Aattack + move + spell (or Charge + spell)
Double move + spell
Spell + move + spell
Full Attack + spell
and, the fully quickened spell wouldn't cause AoOs. So, adding this Feat wouldn't suddenly make the bigger one obsolete, it'd just allow more people to cast two spells per round.