AVC-Intra 50 in FCP

Totally new to HD, need to upgrade and looking for some direction.

Can anyone explain AVC-intra 50 vs DVCHDpro in terms of image size, quality and hours of material per TB of drive space . Also, I watched the great tutorials from Jeremy about native MXF file editing, and from Shane Ross on P2 log & transfer. What are the benefits of editing natively vs the transfer. I liked the look of editing all that meta data, and keeping camera originas nice and organized.

Finally what is the AVC intra work around for native file editing ? Only thing I am sure of is that I need to deliver 1080i 59.94, can do this via aja. Just totally clueless whats the best file type to capture on the camera, and work with in FCP prior to the aja conversion.

We shoot a lot of hours and need reasonable and scalable archive solution for all the material. My budgets allows for the AG-HPX500, but is new AG-HPX300 a better way to go given my storage needs ? Or is it all about the same size. Thanks for the help.

Dave