It is a nice idea, I actually have something similar to this set up for some of my jobs. The biggest thing from setting this up from what I noticed is you need a "reset" button. Why? If you're in the middle of a combo and you have to stop, then you want to revert back to the start of your combo when time runs out.
Right now I'm doing what you suggested through Macros. Luckily the jobs I have now I don't need to switch around a lot. For example I have a base controller set up with Fast Blade. Fast Blade (X)is set up as a macro to reset back to this "base" set up. If I hit Savage Blade, I replace things like Riot Blade with Royal Authority and RoH are there waiting for me on Square and Triangle.
Like someone posted, which I found to be a great idea, is having my cool downs on a bar below my crossbars so I know when to use LR/RL buttons to get to the 8th set.
Though I agree something like this would be wonderful that doesn't involve all the macros..just..don't know how they'd get to where it works.
Of course if you're on PC someone made an awesome Windows voice activation for their Ninja, I took that and put it to my tank when I'm on PC. Stopped doing it because I do servers and tech support..so by the time I get home I don't want to sit in front of the PC for so long.
