The biggest issue I had was going from 30" to 34" within a set (Rob Allen Mouse). I found myself being off by a fret or two whenever I switched. Turns out that can be problematic unless you're playing free jazz.
I have had really good luck so far going between 4 string 19mm and 5 string 17.5mm (E-C). Going from 4 to 5 with the 5 B-G was tougher but it has been a few years since I tried that. I have to admit that the Fodera 5-string neck with 17.5mm spacing is just ridiculously comfortable and seems to be a nice "middle ground". I have no issues grabbing a 4, and likely would be able to handle a Fodera 6 with 17.5mm spacing. I do know that when I've grabbed an Ibanez 6 with 16.5mm spacing I didn't really like it.
I haven't tried a 36" scale, but not sure I want to as I have had issues with some 35"s in the past. Just depends on the instrument though - lots of factors in the ergonomics beyond just the scale length.
I have had really good luck so far going between 4 string 19mm and 5 string 17.5mm (E-C). Going from 4 to 5 with the 5 B-G was tougher but it has been a few years since I tried that. I have to admit that the Fodera 5-string neck with 17.5mm spacing is just ridiculously comfortable and seems to be a nice "middle ground". I have no issues grabbing a 4, and likely would be able to handle a Fodera 6 with 17.5mm spacing. I do know that when I've grabbed an Ibanez 6 with 16.5mm spacing I didn't really like it.
I haven't tried a 36" scale, but not sure I want to as I have had issues with some 35"s in the past. Just depends on the instrument though - lots of factors in the ergonomics beyond just the scale length.

