Would it be a mistake to switch back to already settled Evah Pirazzis 2 days before opening night? I have Belcantos on my bass right now. I switched to them from the Evah Pirazzis that were on the bass because I was having trouble playing arco. The Belcantos helped tremendously in that area, but now I'm thinking about switching back. The main reason is there are a few sections where I need to be louder playing pizz and the Belcantos just aren't doing the job.
IME EPs need a few days, even a week to stay in tune; even old sets (when they are re-installed in a bass). On the other hand when I go back to Belcantos they settle after half an hour of playing / retuning.
Specially if you use strings with different tension I would change strings at least a wekk before you need them (sounding well). The bass needs this time to settle for the new top pressure. Youu might get wolf tones or similar things during the settling time. Even using steel core strings...
Have you tried EP Weichs? Bow & pizz great-as the reg. EPs. You may be happier with EP Weichs. Thinner strings than reg. EPs- big sound.