My concern with the fixed gantry option was how to protect the x-axis rails from the coolant, but having actually thought about it, it's probably easier.

I just need to make sure they're spaced up of the drain tray, and have a lip hung down around the table so that any run-off can't run along and under the table.
Now would you have the rails or the blocks stationary?
I can think of pros and cons to both methods, but don't think it would make any noticeable difference anyway given the sizes involved.