Z-drugs whilst tapering?

For a good long while now, easily a couple of years, I've had serious sleep issues. Around about July/August last year, I picked up some (as yet undiagnosed) chronic headache/migraine issue, which made things a whoooole lot worse.  Between the anxiety of "Oh god do I have a brain tumour?!" (subsequent CT scan says no, happily) and my normal sleeping issues, I ended up on benzos for both the anxiety/panic control and hypnotics for sleep.

I peaked around December '10/January 2011 at 7.5-10mg Lorazepam daily, and typically 40mg Temazepam at night (occasionally 60 after building up tolerance)  Around the same time, I went through a whole bunch of alternatives, including the full house of z-drugs

(Zopiclone, Zolpidem, Eszopiclone, and Zaleplon), Modified release melatonin, and an array of different 'drowsy' antihistamines (promethazine, diphenhydramine, etc).

Nothing really worked for any length of time, probably down to tolerance since I was needing it practically every night to avoid being awake for anywhere between 20-50 hours at a stretch before sleeping "naturally".

I've since stopped taking all of them (except the occasional anti-hist) while I deal with my benzo problems, but I'm wondering if anyone has experience, or can point me at literature about the use of the Z-drugs during ongoing benzodiazepine tapering.

Fairly recently (~3 months ago), I switched from Citalopram for depression to amitriptyline on the recommendation of my psych, partly because it can have a sedating effect, but I've never noticed any significant changes there.

I'm particularly wondering about cross-tolerance/downregulation since they seem to generally be acting on the same GABA_A receptors, and how that's likely to affect my tapering/quitting plans.

I have a strong interest in the neuroscience and pharmacokinetics/dynamics, but my knowledge is still pretty patchy, so I have yet to find anything concrete on how they interact.  The hypnotic benzos and z-* all seem to have a fast bio half-life (8-20hr for Temazepam vs 80-200 for Diazepam), but I'm pretty certain that's not telling the whole story.

So, opinions on the use of Z-* drugs for insomnia whilst quitting? Any plausible alternatives? (Other than those mentioned above)

Any interesting papers/studies/articles to read? (Preferably at the level of "interested sci/eng background layperson who can look up the complicated words on wikipedia", and not behind a paywall )

I can't point you to any scientific papers, but I can give you the benefit of my experience.  A couple of months after I quit Klonopin cold turkey, I started taking Ambien.  I quickly reached tolerance, so I increased my dose, plus took another pill when I'd wake up three hour later.  I was miserable, the inter-dose withdrawal was horrific.  I finally quit Ambien cold turkey, 14 months after my Klonopin cold turkey and felt instantly better.  I can only assume that taking the Ambien was keeping me sick, I believed it was the Klonopin all of those months, but in fact, it could have been the Ambien. 

I understand how desperate you are for sleep, but I hope you'll stay away from the Z drugs, they made me suicidal, something I've never contemplated before.

Personal experience is also good, thanks for the reply.

I have a small quantity of each of the various left from my experimentation, but I'm doing my best to stay off them except in really extreme cases (I hit 65 hours or so and was starting to go a bit nuts).  I figure avoiding them is the safest plan, but I'm curious as to if/how it affects people.