You can't simply drop a P pickup into a Jazz. You'd need to cut a different sized hole for it. Rather than wreck the re-sale value of your Jazz, best to just get a P bass.
Moral is not to let people loose on your kit. If people ask to use mine, I ask them for the keys to their car (probably worth similar). That shuts them up. Hope it's OK.
Scammers? Sounds like an opportunity to have some fun with them if they're trying their luck on here. Check out Ebola Monkey Man's site (Google will find it) for ideas.Hilarious
P.S. albinokiller?Terrible name.Sounds like someone who does terrible things to small furry animals...
Bill's right. The demands/design parameters are very different. If you're a jazzer who wants a mellow, clean tone, a bass amp may do the job. Otherwise, not.
Flightcase 150 is very neutral/clean sounding. 5 band eq - subtle but effective. Mine does a great job. When I need more volume, I add power amp and cab/cabs - it has a pre out. Very happy with it.
In common with FinnDave and Hiram, I'm crazy. Bought a new Mex P Bass Special last year which sounds excellent and plays very well. Had to sort a few minor issues - dress the fret ends, adjust action, etc - but I expect to do that sort of thing with any instrument.
If you have a gigging amp, Markbass may be overkill for home use (although they will certainly do the job and sound nice at low volumes). Then again, it's nice to have something decent if you can afford it (my practice/home amp a PJ Flightcase). Try a few before deciding?
I sold a head a few months back. Buyer asked what sort of guarantee. I said none, am a private citizen, etc. Demo'd and got him to declare himself happy before taking. End of story.
I'm a Gotoh fan. 201 mainly, but they do the 203, which is a more solid version of the traditional BBoT, which works well. Have one on my fretless. Don't like the Badass - seems to rob the instrument of warmth.
As others suggest, you could stick with current band for the social/fun side and do something more satisfying too. Have you actually tried saying to the current band "love you dearly, chaps, but cannot carry on like this". Might wake them up to the need to improve. Or are they a lost cause?