Replying to Karl...
I realise that the very mention of the name Alembic automatically gives us high expectations, especially when you consider that John Entwistle apparently managed to get his Alembics to do what you are trying to get yours to do. But I have to say that the action you're striving to maintain on that bass of yours seems murderously low - I can't imagine how refined your technique must be to keep that thing under control when you're playing.
I have small hands. Even though I'm (obviously) male, I really do have small hands. I buy mid-size watches as normal gents' size watches are far too large on my wrists. Hence, I find that I cannot play basses where the action is too high - my wrists ache and my fingers ache too. That's why I've always stayed away from baseball-bat neck Fenders, not to mention the fact that I really don't like the poppy sound that the split P pick-up gives. My 4001 is fairly low, 1.2mm on the E and 0.9mm on the G.
Regarding technique, I don't understand the fact that playing an action that is regarded as being low is so difficult? I just play the damn thing - I have a very light touch, in fact it's so light that you'd swear the strings don't move! I let the amplification do the work, not my fingers.
I could get into a competition as to which of my basses are lower than the others, but that's not the point of this thread.
The facts remain that I can set-up the DW to play with an action of 0.8mm or thereabouts (it will go lower!!!), with a virtually flat neck (i.e. next to no relief). It plays absolutely beautifully! It won't necessarily be like that in a few hours time! The time frame is too short for those sorts of swings to take place - in my mind anyway! If I'd taken it out of the house to whereever, then I accept a change of state.
Interestingly (and as I have stated previously) since the weather here has been hot-ish, it's been fine.
I used to think my action was low, but it's nothing like that, and in fact, I've found that by raising it a touch I actually get a better tone - the string can resonate further without the frets interfering. I started out trying to emulate the (apparently) ridiculously low action of some of my heroes, but over the years, I've developed my own sound by moving away from straight aping of their technique and set-up, and I believe that's a positive step.
I'm not aping anyone's set-up. My basses sound fine too, there is nothing I can gain from increasing the action - I've tried it. I do the low action thing because I have small hands - if I have to struggle to play an instrument, then I simply will not play it.
I learnt to play on a Fender Jazz (starting in 1979) and it was all too large for me - I could quite happily have given in. Hence the reason I played and subsequently bought in 1981 the 4001 that I still have now. When I wanted a second bass, I looked around and settled on a JayDee. The reason I bought a JayDee was because the action was very very low on the used one that I played but the new one I had delivered was hopeless.
However, I realise that if you're in a top-flight Who tribute band, then you're in a very different position - you're being paid to emulate your hero's sound and technique, and of course, having your bass set up as his was is all part of that.
I'm between bands. No-one is paying me anything, unfortunately!!!
It's a tricky call - on the one hand, yes, I'd say your expectations are high and you should try backing off a little and let the bass play the way it wants to, but on the other hand, if any bass should be able to meet those high expectations, an Alembic should (as John showed).
I don't do back off - one of the major reasons I bought an Alembic was the fact that the action can be set-up lower than a snake's belly! Just to prove a point - my Status Stealth has no relief in the neck, the action is 0.8mm on the E and 0.4mm on the G. The Dragon's Wing will also do this, but the instability is just too much.
The DW is as low as anything I own at the moment and it's a joy to play - it has been for at least two weeks (that's a major gain over the three-hour slots I've had in the past). I wonder what will happen when the weather takes a nose-dive?