Oh, I've done quite a few setups before. I've got a set of allen keys and I'm not afraid to use them. I'll try and explain my reasoning to you, (and myself).
I want a full time luthier to do this because; a) they should be better at it than me, and b) because it's difficult to be subjective when adjusting an instrument for your own use.
If I do it myself, I'll be trying to make the bass feel familiar or 'right'. These adjustments could take months, years or forever. If I tell a luthier how I want it, when I get the guitar back, (depending on how good a job I think they've done), I'm more likely to accept the instrument for what it is and adjust my playing style subtly to suit. Then I can just restrict myself to the twice yearly seasonal truss rod tweak, and use more brain power trying to play the damn instrument rather than trying to fettle it.
I put Labella flats on all my basses, (yes even Stingrays it seems), and only once. I'm probably more likely to sell a bass before swapping new flats for old.
I've always been happy to take an allen keys to a friends bass when asked, because I can be subjective and I don't have to live with it every day. Also, under the proviso that I am very much an amateur and that a pro luthier will do a better job than I could.