I'm using Vegas Pro 10c and the new Boris BCC-7FX for VP 10. Having some problems, see my post under Sony Vegas pro 10, and can tell you that Boris Tech services will reply, but takes a long time to get back, Then a question which I answer right away only to wait a few more weeks to hear again.
I have not tried all the plug-ins, but the ChromaKey is great with all the matte and lighting stuff so this is not a bad mouth of Boris... unless more fail as I use them.
Just think about your decision and don't think either VP 10 or BCC 7 for VP 10 is finished sorting out the difficulties. Further is you do not have 64 bit I would be extra carefu.