Worthless info for you:

1) We just started helping a client that uses jQuery mobile and we despise it. Your problem with it is just one item on our long list.

2) There is one such list out there that I've seen but it is huge. I don't see the point anymore since even that can mis-identify devices though I'm sure it's rare.

Everything we do is responsive nowadays.

Agree with drhowarddrfine, responsive is the way to go...(just my opinion).

I prefer Bootstrap as a framework.

Thanks for your input, guys! It's interesting, a second time in one day Bootstrap framework is mentioned in positive way in different threads I posted to. Given that it's also a framework like JQuery Mobile, and also requires learning a new meta-language, what do you think makes it better? Bootstrap's grid system seems a big deal but everything else looks like analog of one another, just a bit different looks. And, again, JQuery Mobile just looks too far gone to the mobile side, Bootstrap examples I've seen so far look like they may work on both...

I have to say that developing for BOTH desktop and mobile at the same time is appealing to me, too, but my earlier attempts at responsive design ended up in a nightmare of cross-browser testing, hence the two separate sites. That is not a much desired situation either, more like a compromise. I've yet to research and appreciate the difficulties of two-site SEO, especially duplication issues.

JQuery Mobile just looks too far gone to the mobile side

Perhaps thats why its called JQuery Mobile?

Perhaps thats why its called JQuery Mobile?

LOL, well, sure, but Bootstrap is called mobile-first front-end framework. Also, it's not like a JQM site is not functional on desktop. It does work, it just looks too cute and over the top. On a mobile phone though, their propensity to make EVERYTHING a button kinda works.

I don't know, I'm browsing through Bootstrap examples on a smartphone and I'm not quite getting that feeling of it being well designed for touch. It seems suitable for small screens, sure, but the things that are supposed to be touched are kinda more inviting in the way JQM renders it. I suppose everything can be CSSed but then why would you use a framework ...

The client's programmer says he's using jQuery mobile because he likes the way it styles the buttons and that's the only reason!

a nightmare of cross-browser testing

Whenever anyone says, "cross-browser" they mean, "It doesn't work in IE".

who knows a reliable (and regularly updated) library of user agents for redirection based on agents

It may come out better if you check in the other direction. If the user-agent is {short-list-here} it's a browser. Anything else and it's a mobile. Save the hand-coding for tablets; luckily there aren't many.

FWIW, not knowing what your site does, Google recommends a single RWD site, not a separate site for mobile so if you can just make your code change it's appearance for mobile and not redirect, the way Twitter Bootstrap does, you might find life a bit easier.

nightmare of cross-browser testing,

Here's the big problem with mobile, there are TOO MANY BROWSERS!
Chrome, Dolphin, Firefox, Opera, etc. but the only saving grace is Apple webkit being common among all of them and those that do something different these days is a why bother.

Plus WHICH version as Android phones are always being abandoned so you have people running ancient stuff on Android 2.1 (or worse) or the current stuff on 4.3 that I'm now using.

Not possible to test everything but the most current Android and iPhone so since almost everything except Windows 8 uses Apple Webkit I don't really bother with the full blown testing of everything as there are simply too many things to test. Does it work on both iPhone and a Galaxy or Nexus 4? iPad and Nexus 7? Done.

Often I find I don't even care about Apple stuff and just test Android these days except for a cursory glance on the iPhone now and then unless people send in complaints.

That's why we do a beta period and let users do a little of the testing :)

Apple webkit being common among all of them

Webkit is Safari and Chrome only. Chrome has moved to Blink, a fork of webkit, and so has Opera but Opera never was webkit. Firefox is Gecko. So only Safari and Dolphin will still be on webkit soon.

I don't even care about Apple stuff and just test Android these days

iPhones still make up almost half the mobile phone market. Opera is big on mobile and is not webkit. Firefox is coming on strong on mobile and is gecko.