I know what I’m about to write won’t be popular since, in my own work, I hate it when someone throws that question at me but… I have also find it useful to address the question so it’s in that spirit (constructive criticism) that I’m raising the question.
There are basically two strategies to migrate to a new framework. One is the big bang, which is your current strategy, i.e. a full rewrite. The other one is gradual rewriting, while adding new features. For example, the migration takes place over the course of the entire 2.x development. The groundwork would be done in 2.0, but some stuff would remain old code (relying on a common database, of course). Migration continues in 2.1 alongside bug fixes. 2.2 adds new features and some more migration (one module at a time say), etc.
Both strategies are extremely frustrating because basically, as you said in your post, the underlying work is not glamorous and is frustrating but the big bang is typically choosen because it appears to be the easiest and fastest solution.
However in most projects the big bang causes you to loose competitiveness against other products… up to the point where a gradual migration actually makes more sens… despite its numerous shortcomings (and I know the shortcomings, and I know they appear unsurmountable until you have a real hard look at them).
So, after this introduction, my question is: are you sure the current strategy is the best one for the product and the community?
While you are working on the migration, other CMS are making progress feature-wise (MT has added custom fields, for example). More importantly 2.0 is not supposed to be feature-neutral, it is supposed to introduce the full commerce module which (if I read the forum posts) many people would consider a very worthy addition.
Please understand that I am not urging to change strategy. That would be presumptuous for me. But I’m asking have you considered all the consequences of the fact that you understimate the time it takes to migrate? Have you considered the alternative scenario?