I played Merlin last year for I&E. The piece had to be spliced quite a bit to make the 4 minute time limit. It also had to be transposed up an octave in many places and several of the left hand intervals had to be inverted towards the end.
I doubt that you will find many peices any more that you will be able to play straight up. You will have to test your skill as an arranger as well as a performer. Some corps have extended range marimbas, that makes things a little easier, but 4 minutes is hardly enough time to sell a piece in my opinion, Anyway, good luck.
-Ray Laffoon
Cavaliers marimba 2002-03