While it'd be nice to have a fifth gear in an Elan the advantage that the Elan has over other British cars of the period is that it has a fairly decent fully synchromesh four speed Ford transmission, with a gear shift lever that goes directly into the transmission with no external linkage so the shifting is pretty nice.
I've got a Vitesse conversion in my 1964 MGB and it's amazing. The trick with my car was with the early three bearing engine, a bushing didn't fit properly since the kit was designed for the slightly later five bearing engine. No worries! Moss contacted Vitesse, who scratched up a new bushing and voila problem solved. I also appreciate that the upgrade is basically invisible.
If this would fit a Healy 3000, my father would've loved that. He wanted one of those cars badly, but they shifted so roughly, he could never sell my mother on "letting" him buy one. He used to say " the sawdust had leaked out" of the one he had driven.
Never thought the gearshift in my MGB or TR6 (both with overdrive) was anything but fine. I feel no better gearshift in my Z4M, so I guess I will stick with the originals, if and when repair/replacement is required. The seemingly unbreakable Moss box in my Mog is a different story, slow changes, but positive feel to the changes, just don't be in a hurry. I can think of many other ways I would spend $5000 on my toys.