We have a project that needs to be mastered in HD.
One option is to upgrade our SD-DS to HD, we already have the software upgrade to 7.6, or purchase a FCP-HD system to do an offline, then online on the DS-HD we currently have.
It comes down to cost of the HD dongle vs. the FCP-HD system. I have no idea what the dongle costs (anyone have a rough idea?)
The project was shot in HDV and has to stay that way through the edit process.
DS does not do native HDV so you will not be able to stay native HDV throughout the entire process. DS will do the online as uncompressed HD or as DNxHD coming from a HDV to HD-SDI converter such as the one from Miranda.
If DS is going to be the online finishing system, then I would suggest you consider using Xpress Pro as your offline where you can use AAF and AFE for a much better conform (including titles and FX) than you would get from FCP to DS via EDL.