I gave thought to this many years ago because as I motorcycle guy / racer first I've always thought H pattern gearboxes are an abomination (no strong opinion there)

So here is my deal on sequential boxes; with the motorcycle powered sports racer once I left the pits I'd go up and down the box with out using the clutch. This naturally allowed me to left foot brake. While I'm capable expecting flawless heel and toe downshifts I don't get any big thrill out of it in and of itself.

On the surface it seems simple enough to come up with a shift drum mounted externally to move the shift lever but what do we gain from it........ Besides the cool factor of course.

One possible thing I can think of is paddle shifters making it easier to keep hands on the wheel while shifting.