$400! That's practically stealing it! Good for you.
The High Power is a great match if you can mount the pj either on a table in front of you or on a shelf behind you close to eye level. The screen is retro-reflective, meaning light will bounce back off the screen where the light came from, sort of like a reflective street sign. The MKII has lense shift, so this can be easily accomplished.
The great thing about the MKII/High Power combination is that with the MKII in high contrast iris mode, the light out put is pretty low, yet the contrast is very high. With the High Power screen, as long as you are fairly close to where the projector is shooting from, the light from the projector will come back to you up to 3 times brighter! Thus, a dull image will all of a sudden look very bright, yet you will have the benefit of running the MKII in high contrast iris mode and economy bulb mode. High contrast AND high brightness at the same time.