Your problem has been discussed a lot.
There simply isn’t a 720 p25 solution out there as of yet.
Hooray!
So what to do?
Some suggestions:
Shoot the HVX at 1080 p25. Then you’re OK.
Dump through an AJA that can upscale to 1080 psf25 (p25 in an i50 stream) like you would with a varicam/AJ 1200 solution. No Firewire for this one…
Wait for the NLE people get their act together and remember that the US is actually not the whole world.
Send a polite mail to the BBC. They use a lot of HVX’s together with FCP, but I suspect they’re going the 1080 route.
We’re quite a few in your shoes right now, so don’t forget to send a polite request to apple on their feedback pages.
Gunleik