I had one neck like that, but I returned it for other reasons. Just to be clear, is it bowing so the middle of the fretboard sits higher than the 1st and last frets (convex) or is the middle lower than 1st and last (concave, like what you would expect from heavy strings pulling on it?)

If you are all the way at adjustment from it being convex, I would say that is OK. The tension of the strings will pull it back and you have a stack of adjustment back to fight the string pull. If you are all the way at adjustment from concave, then any further adjustment after you put the strings on will be impossible, which is not ideal and probably worth returning. Does that make sense?