Why not use a custom built USB/firewire based RAM stick with the executable program and essential files loaded on it as a dongle? The files could only be launched directly from the dongle with built in encryption based on unique identifiers in each dongle.
The upsides would be in my mind:
Less hard disk storage and usage from the host.
Fully portable sequencer, you just get one piece of hardware which could be used on multiple systems.
Fast execution speed due to being stored in RAM (or would the interface slow it down too much?)
Downside? Losing the freaking thing, I guess
What say you?

