If your main motivation is sound control, then have a look at the ECoS from ESU. As they appear to have built their business on their LokSound decoders, their claim to have added comprehensive sound control to the ECoS seems entirely credible. The only feature I can think of off the top of my head is using the joystick toggle to control the length of the whistle / horn blast on a LokSound. If that idea is appealing, try to see the system at a show where the UK distributor - South West Digital is exhibiting. Since SWD have their own range of diesel (and 1 steam) sounds based on LokSound decoders, they should be able to give a convincing demo.
David
David