I've always favored shorter scales in a 4 string. My old Spoiler was and my new bass is a 32 4 string. I love, em. Very easy on the lower frets, precise, but manageable on the upper. However, I'm leaning toward a 34 (even a 33?) when I Alembic builds my 5 string. Not because of sound, but because of the greater ease of fingering the upper registers on a 34.
I've found that, for me, neck width and thickness are just as important as scale on a 5 string. Alembic's Comfort taper 5 string fingerboard 1.875 nut, 2.930 24th fret) width is a bit wide for me. However, Alembic will build what you want on most models for no extra charge.
I like the width and thickness Ibanez uses on its Soundgear 5 strings better (1.77 nut and 2.6 24th See
http://ibanez.com/guitars/guitar.asp?model=SR405 for an all dimensions diagram). Others have said the same. I plan to try a number of other 5 string necks and dimensions before I'm ready to order, but having owned an Ibanez 5, I'd say it's pretty close to what I want.
The other variation I've considered is building the neck assymetrical, with the thicker part under the low strings. I think that might relieve a little thumb fatigue, but I'll have to find and try one with that shape before I decide.
Bill