I read a comparison of two cameras. One of them a camcorder which records MXF files (=mpg2 50 Megabit/second). The other one DSLR, Canon EOS 5D Mk II. It was not clearly stated if it exports mpg2 or mpg4. The bitrate was given as variable 40-50 Megabit/second.
As far as I can see, it is impossible for Premiere Elements to handle MXF files (unless converted to 25 Megabit/second). But can Premiere Elements handle the datastream from the other camera? DSLR is rapidly becomming popular, so I guess many want to edit the footage with Premiere Elements. I mean edit and export without converting to some format which results in loss of information.
PrE 9 has DSLR Presets that should work fine with the Canon.
For MXF, you would want to look at PrPro CS5 (which also has DSLR Presets).
Hope that helps, and good luck with the decision,
Either format is going to require a "strong" computer... similar to editing AVCHD
Intel i7 950 with lots (1) of ram and at least 2 (3 is better) 7200rpm hard drives
PE is 32bit, so a 64bit Windows and over 4Gig of ram is not really needed
Premiere Pro CS5 is 64bit, so Win7 64bit Pro and at least 12Gig of ram is the "effective" minimum