I have a Mitsu WS-48413...so basically we have the same set other than yours is a 55in and mine is a 48. According to my manual, the 48413 has a DVI-D port. Though looking at the port, its 29 pins total...so I would assume it can go either way. Though, I'll probably go with DVI-D.
Diffs between DVI-I and DVD-D
DVI-I contains both the digital and analog connections within one cable. DVI-D and DVI-A cables within one cable.
DVI-D is pure digital. If both devices (TV and 811) support DVI-D, are compatible in resolutions, and are in sync, you will be using a pure digital connection between the devices.
In our case, the 811 is DVI-D as well as the mits 48413 and 55413, so we should get pure digital connections. Just remember to set your 811 to 1080i output for the DVI to work as the 811 comes set to 720p!