The Preset 10 behavior is described pretty well in provided link. Since it is fading all DMX values at once and not just the intensity channels of the fixtures, it might not look right until it has completed the fade. You can record fade times as well.
I've had this unit installed at many a school lately. It pairs extremely well with 6-8 CS4's and a CS20 board. As long as you don't exceed the 512 addresses you can put as many items as you want.
Fade time doesn't matter because they would be set at the beginning of the event before people would get in there. And would stay on until the end...unless it needs to change in which case they would be able to just flip over right away.
You might want to consider the relatively new Preset 10A-POPO as it allows you to have more than one preset active at the same time (HTP).
Could possibly give a greater variety of "looks" in this application. Instead of canceling the last button when you press a new one, the
"Push On/Push Off" version lets you select any or all presets as active. Depends on how simple you want it to be, but with the LED "on" indicators for each active preset , it doesn't seem like it would confuse people too much.