Have any of you guys tried capturing 1080i HDV footage into ProRes and edited on a 720i timeline? I could see some advantage in being able to re-frame some shots if necessary or add some movement to static shots. I know that some have tried working on an SD timeline with poor results due to FCP scaling but I have not heard of anyone on here using the 720i timeline.

Didn't do that. I just mixed 720p and 1080i into a 720p ProRes project. FCP scaled the 1080 footage into 720 automatically. It worked seamlessly although I guess I could have zoomed into the 1080 footage a little bit if needed.

Thanks William for sharing your results. Anyone else? I'm planning on doing this on a project coming up so I will report my results.

Yeah I've done this. The HDV footage was from an HV20. I brought the clip into AE and de-interlaced and simultaneously converted to Pro-Res 720p @ 23.98.
-C