If it were streetable for the life of the bike I'd probably be in. Otherwise we have already scienced out less convenient (but utterly reliable) dual sprocket setups.
Speaking for myself that would limit it mostly to a direct-driven gearbox. Not into jackshafts, multiple chains or swingarm-mounted gearboxes.
A lot of us are fairly familiar with most of the prior art. Might not be a bad plan to get some input.
Regardless of design, we'd all dig seeing it.