So Great Haste's impact on play has prompted another GM to limit it a bit:
Gimping Great Haste.
My players and I - mostly the players who routinely take, and cast, Great Haste - have discussed ways to limit the spell.
Lessened Great Haste for example, is a list of some ways we've considered changing it.
The method used on dripton's blog is a simple one. Still, I feel like it weakens fighter-types - which is fine - while not limiting casters - who really, in my experience, benefit from Great Haste. I'm not saying his choice is wrong, just that it's something I think my players (especially the ones who run Dryst/Angus McSwashy and Gerry/formerly Vryce) would have concerns about. Great Hasting yourself as a caster is a turn one move in any fight you expect to last longer than 10 seconds, against foes who need to be defeated by magic, or against a foe too lethal to make it last 10 seconds.
I keep looking back at my post and trying to figure out a good solution. I like the idea of double abilities, but it's tough to adjudicate in some cases. The fixed bonuses is nice, but perhaps too limited (and needs to address casters, honestly.) I need more feedback from my players before I can really do more - they love Great Haste but more than a few of them find it so must-have that it could use adjustment to make it feel like a more balanced choice.