Bobstah made his Battle Status Extended plugin compatible with mine, for those that might want a different Status Window layout (it's pretty neat):
http://forums.rpgmakerweb.com/index.php?/topic/49459-bobstahs-battle-status-extended-11-atb-support-vertical-gauges/
An idea for handling Haste and similar states would be a notetag that affects ATB speed that can be put on states (among other things), and then another notetag that changes the color of the gauge. Might be too complex, but it would allow a lot of customization. A separate notetag for affecting cast speed would be nice too.
The idea of ATB Speed and Cast Speed was basically what I had in mind:
We would have three attributes changeable by states (and equipments):
<haste:>
<haste_atb:>
<haste_cast:>
The default value of each of them would be 100 (as in, 100%, normal, speed).
Haste would be the general speed, affecting both atb and cast. The other two would affect only atb or only cast.
I hadn't thought about the idea of having the color gauge change as a notetag. That's a good idea, I might give this option.
Another thing, I'd also have to allow a state tag for something like:
<state_atb_duration:>
To make states with duration based on flat atb amount, instead of turn timer or action end. Those would work much better for "Stop" style effects and such, at least, and I'd recommend using that for almost everything actually. And to further support it, I could also allow the maker to customize a different stat to be used for state duration reduction (so that MDF may reduce the duration of a negative state effect, for example).