My personal opinion...Vista does what it does, but i wouldn't use it for production because all my software hasn't been ported yet. 8gb is not overkill, especially when using the kore2/komplete5 bundle. Kontact 3 will swallow 4gb pretty quickly when you begin layering sounds.
If I was primarily using software i wouldn't use Vista until all my software was available in 64bit versions and I could get atleast 16-32gb of ram to use. 64bit Vista Home Basic is limited to 8gb ram, Home Premium to 16gb, and Business, Enterprise, and Ultimate will get you to 128gb. My rhetorical question is how long will it be before 128gb is not enough?
I don't see an advantage in moving from 32bit WinXP to 32bit Vista at all.
Now since i am primarily hardware based, I can get away with using Vista as i only have to deal with the midi and the audio, no VSTi's, so to speak.
I personally would hold out as Windows 7 is coming, but dont fall for the Vista is crap comments that people are saying...if your software has 64bit versions AND your hardware, audio card, monitors, etc, have 64bit drivers then I think vista is worth checking out.
A good read for XP vs Vista for production is
http://www.dawbench.com/