This is an old post but this may help. I’ve shot some footage in 1080i HDV, brought into FCP and export out with current settings. I’ve then used compressor to send to H.264 6.75Mbps under HD DVD: H.264 90 minutes and got a fairly good quality results (approx. 60MB per minute of footage)
This format is incompatible with DVD Studio Pro but you’ll find you can import this into iDVD ’09 and produce a SD DVD which you’ll be able to play on pretty much anything with a reasonably quality. Problem is you stuck with using iDVD for your menus etc, which I appreciate is not ideal.