I'm getting itchy about the official update as well. Rooted my last phone and spent more time than I wanted fooling with things. I also never knew what was to blame if something was squirrelly (hardware or firmware?).
That was part of the reason I chose the nexus. I just wish we had some concept of how close we were.
At this point Google should just strip out Google Wallet and Google Voice integration and give y'all the update.
Nobody would complain about that ...
You have misunderstood ICS. Google Voice is not integrated into ICS. For ICS, they made new APIs (that are available to any voicemail provider) that allow hooking into the main parts of the phone (missed calls, contacts, voicemail lists, etc). They also happened to fix Google Voice to take advantage of these new APIs, but Google Voice is a separate application and the API/intergration is available to Visual Voicemail, YouMail, etc as well.