We have painted our murals on movable flats for two reasons:

1)  We are currently contemplating a move to another building.

2)  We like the idea of being able to change up our rooms.

Normally the murals are left up where we put them but we have built in flexibility for all the time that it takes to do the murals.

We have even moved some of our murals to the sanctuary to be used in plays and placed them on a huge 12 foot by 8 foot high colapsible profesional display.

I agree with painting walls vividly and we have done some great faux finishes but as for actual murals... I say keep the flexibility and watch how many ways you can use them.