Anywho, I say go for it. Frank would be cool and ironic. That would be so awesome. But I can go for someone else too... really I have no preference.
I think some should just let the fact about Megatron as a handgun and Soundwave as a boombox go. It's great to do in G1 and completely original, but not a good idea for the movie. A movie is supposed to be realistic and the handgun transforming into Megatron defies the laws of physics.