DO IT!
I think my bass fund is adequately depleted for the foreseeable future.
I do like a "modern" sounding bass for some of the things I do. I like it for a lot of the worship stuff I do, and I have another part time project that it works well for also. That's part of the reason I have missed my Q5 so much. But, I think that reverse PJ does an amazingly high-quality modern tone at center detent, VTC dimed, treble flat and bass just barely open. It is definitely the one "needed" tone that I can't get out of that SC JJ I just bought. (Plus, I think the PJ has has a better B string than the JJ, but I am holding judgment on that until I can compare with like strings. )
If I did get an M5, I would, no question, have to part with my PJ-r or the JJ. Neither of which is really palatable for me right now.
I can't remember the last time I actually played above the 21st fret. I don't know that I ever have in an actual performance. So, that isn't really an issue. I think it is just a looks thing. They're just so hot looking.
I really want one inspired by my Q5: 5A quilt top on alder. No tint, just clear on the raw wood. Ebony fretted FB and chrome HW -- just in case any of you guys win the lottery and declare "Sadowskys for the lot of us!"