BD and HD DVD are basically software layers. If at some point everone can just agree to use the same disk, we can simplify everything. So if you want iHD and HVDIDEO_TS folders with EVO files or if you want BDMV folders with mts files, you can, just make sure they use the same storage medium --- that would be the 50GB DL one.
This way, those EVO files can be encoded in VC-1 with peaks of 40Mbps for video too. This should make everyone happy, yes?