tinyd

That's a really good analysis. I found my copperhead to be very usable as well - I just upgraded recently to a Lifeline because it's a bit less bassy on my bass. I did some similar experimentation last night with an FDeck HPF and a Fishman Platinum Pro (the old one). I tweaked a lot but I came to the conclusion that the best sound is just going straight into my amp (a Warwick Gnome head and a Phil Jones C2 cab). The only thing is that I have to turn the bass and middle all the way off on the amp. The HPF and preamp do give a bit more control, but I end up just doing using them to do the same thing (turn the bass right down) so once I took them out of the signal chain it didn't really make a difference. Anyway, I think the moral of the story is that it's worth playing around with different gear, but probably the most important thing is getting the right pickup (or mic) to provide the best possible input.

+1 on the Realist Lifeline. I've tried quite a few pickups over the years and this one is my favourite so far although I also have a J-Tone as a backup. With careful EQ (i.e. killing the mids) I can get the Lifeline away from that "fretless" bass tone so it sounds pretty natural.

It's obviously good to play with drummers but like @NickA says above, playing without them is also really important. It's also nice in a rehearsal/jam situation because you can usually play without an amp which I find good for my overall playing. Also, of course, not all drummers are created equal so sometimes adding a drummer is detrimental....

One other thing - while you have the strings off, use a 4B pencil to add some graphite to the string slots in the nut and bridge - it helps lubricate them slightly when it comes to tuning.

Yep, same (except my bass is a hybrid). In my experience feedback usually happens if the amp / pickup / preamp setup isn't optimal - but once you can eliminate the "boomy" end of the spectrum it's usually fine - certainly for jazz/bluegrass type volumes.

I don't have opinions about bass players' ability on guitar, but I *do* find that guitarists who pick up a bass often have a bad tone (because they don't pluck the strings properly) and their timing can be dodgy.

Yep, the vamp thing is key I think. I saw a Pee Wee Ellis interview and he called out So What as an inspiration (the horn line) but I think the modal jazz influence is there as well in terms of staying on a single chord for longer.

I have a Warwick Gnome head running into a PJB C2 cab and I like it a lot. I use it for DB and it's loud enough for small jazz gigs with drummers plus it's very light and so easy to carry.

I added small side markings with nail varnish a few months ago purely for gigs where hearing myself can be challenging. I hardly ever look at them but they occasionally help as a sanity check and can provide a "safe place" if I panic..... Of course, you can call this a crutch, and adequate practice and consequent muscle memory should remove the need for them, but I like having them there all the same.

I thought that those little battery powered Roland combos (Micro Cube RX) were supposed to be OK for upright, especially for what you say you need it for. Edit: Looks like the RX is discontinued and has been replaced by https://www.thomannmusic.com/boss_dual_cube_bass_lx.htm

I own a Platinum Pro and an FDeck but I always had results that were fine going straight from pickup into my amps (formerly GK MB150 and now Warwick Gnome). This is true for all the pickups I've used, including a J-Tone. I'm not saying don't get a preamp/HPF, but I'd try without before spending money on one.

I had one for a while from @benbastin - it worked very well and the stability / simplicity aspect was good. However, my daughter started learning DB so I needed something adjustable again. I didn't notice any difference in sound but that might say more about my ears than the endpin itself....

I read some comments on Talkbass about the Rumble combos being good for DB...

In my experience, people who have something to say that's worth hearing generally don't offer their "wisdom" unsolicited like this....

That's really bad. What's wrong with some people that makes them think this in any way appropriate? At the end of the day, your singer has the gig, she's getting up there and performing, and anybody who doesn't like her singing can go and play their own gigs. I hope she's ok.