for me, the neck is the deal. If you have a bad neck that is uncomfortable to play, that's the ballgame I play 5s and have 3. Love each of them. - Oh, and I do have a BEAD 4, (see avatar pic) that is super fun to play. Anyway, only reason I mentioned all that is that I didn't buy any of them without knowing if comfort was a go or not.
I have a Schecter 5 that has a real flat radius (how curved the fretboard is), it's like 16" or something I think. The neck is narrower than my VM Jag V, so that works. Now the Jag V is a little less wide than a P, but not as narrow as a J, but the fretboard radius on that one is 9.5", so it's a little more rounded and less flat, so that works. Won't go through all of them, you get the idea...
If you get something uncomfortable, you won't play it, so don't peer pressure yourself into a 5 if you don't feel good about it. Plenty of great players don't prefer 5s and you hardly ever see them with one. Ibanez makes some pretty comfy playing 5s, so if you can go check one out. Sounds like you are hip to the whole getting your bass set up thing, so even if you buy new, go to someone good that can put on a fresh set of strings and fix up action/intonation/neck relief, etc...
Hope this helps!