Lululee, not to put more pressure on your shoulders, but once you decide to get Complete, you're stuck with it. There is no upgrade/sidegrade path from Complete to Infinite.
Be sure to read very well the comparative chart, I know a user was very disappointed that HDR maps couldn't be altered in Complete (luminosity/contrast).This feature was very important to him, and by bying Complete, he lost it permanently.
And as far as "beta testing" goes, there is no such thing with Infinite, even if you hear the opposite. There are a few glitches and bugs, but it is 99% rock solid imho.
The Poser problem on the mac gets people furious, yes, but those how use Vue as a professional tool couldn't care less about Poser. I remember Eran Dinur's comment when Vue6 was shown at Siggraph that he didn't get a single question about Poser import.
Complete is still a Pre-release, so I suppose there are more problems in it atm. And no python yet (e.g. SkinVue), though it will be implemented according to the Complete feature list.