I went from the basic Spider to the L35 Ghost Spider and there was barely any transition period at all. Same speed meter, same scales with the addition of a 15 foot one, it's really the same stick only a little better. It'd probably be a pretty easy transition to the L66 GS, too. I tried it out during the free rentals, and the meter is just slightly faster, but other than that it felt just like it's younger siblings.
I also tried the Daytona during the free rentals, and it would take some getting used to. Different scales and a slightly faster meter, of course, but the lines to either side of the ding line move in closer to each other, too. I use those marks for aiming, the so called miss the ding method, so I didn't know exactly where I was aiming with the Daytona.
I seem to have fewer lip outs with the L35 GS, and my stats are slowly improving, however they were slowly improving with the old red Spider, too. But I haven't used the L19 since buying the L35, and recently went ahead and sold the L19.