Most all orchestra strings are made for standard tuning so its not going to sound all that good, especially for double bass.
Higher tension stings for electric can be tuned down and still sound great though.
Lowering pitch does sound much better and more emotional imho. That's why part of the reason why baroque tuning was A=415h, also its much easier on the human voice; 440 is way to high for our voices! You have to give yourself time with it. The intervals sound much 'looser' and easier on the ear.
There's a whole conspiracy theory about why the Nazis implemented concert pitch to A=440hz.
well, sort of. Baroque tuning was low, due to the catgut strings they used and the instruments that had 6 strings or more - a lot of tension on a Viol or Viola de gamba neck. The predecessors to the piano - harpsicord, etc., weren't built well enough to handle higher tension, either. 415 is interesting to hear- it feels very relaxed and sonorous, due to its darker sound. I used to go to early music society concerts, played with Baroque era instruments, (synthetic catgut strings- PETA would have had a fit) tuned down to 418.