I'm part way through the process of getting shot of a 3.2 V6 Vectra, (long story...) and have had a run in a VXR.
The VXR is pretty swift in a straight line, but TBH even the post 07 models that had a few tweaks, aren't great handling vehicles on the twisty stuff. It'll like a drink as well, so depending how your fuel is funded that may be something to consider, although with a manual 'box and a light foot you should be able to see late twenties, early thirties on a run. The autobox AF33 has some well documented and expensive issues with it, (Google AF33 +vectra +problems), and although I'm honestly not sure if you could spec a VXR with an auto, I'd be steering clear if I came across one. On the plus side, both the estate and hatch have very decent sized luggage areas and the V6's give near silent cruising on the motorway. Nice Recaros too :)
I'd personally give it a miss.
drivethedeal.com have Octavia VRS deisels with a 20% saving - about £16k all done.