I've asked the same question and have gotten no answer from sofo/sony. would be nice if we got some sort of answer. Since the SDX900 supports capturing DVPro50 or DVProHD via existing firewire.
I'm hoping the critics are not right about Vegas becoming Sony centric.
I believe SoFo did answer that question some time ago.
You can edit it within VV by using a codec available from Matrox I think.
You cannot capture or PTT. I seem to remember that there was a faint hint in the breeze that DVCPRO 50 support might happen.
Because firewire is only a data pipe, VV needs to know quite a lot about the data coming and going on that pipe.
1) How to control the transport
2) What format the data is in.
To further compplicate matters early DVCPRO machines didn't have firewire interfaces, as far as I know none of the DVCPRO 25 VCRs have it, some of the PVCPRO 50 VCRs do. A better way to go is take component / composite out of the VCR and feed that through a A/D box and into VV