When I now come to review the market, I (mistakenly) had some expectations based solely on VOIP having been in NZ for 10-odd years and on Telecom/Spark being a large Telco. I just didn't dream that they would still be at the testing stage of a development that they must have been able to foresee for more than 10 years. My fault for making assumptions ;-)
On bundled VOIP & broadband being better always - isn't that likely to be wishful thinking ? I tend to find that ISPs get lazy and rely on the inertia of the customer base to accept a lesser / more costly service component - just because it's part of the bundle.
I'm sure you are correct that tagging is easier (or only possible) when the ISP is handling the voice packets - but doesn't this advantage evaporate as soon as the packet gets out of your ISP's own infrastructure and into the big bad world ? Experience with WXC (donkeys years ago) and Skype (more recently) indicates that occasionally bad stuff happens - and you just re-dial. Of course, that's true on a POTs call too - since it's been some time since that was copper end-to-end.
To keep the 'land line' bundled with the UFB: a quick comparison of Vodafone & 2Talk's VOIP service indicates an almost 200% premium. (VF = +20$ over naked UFB +10$ for Vmail, ID, etc; 2Talk = 11.50 all up). So, for lowly residential land line use – is this premium justified by superior tagging ? For me - probably not.