sanyo plv-z2000 what screen/gain is best

[shark420]

just got this, upgraded from a z4 and want to get the best screen. I have a grey wolf screen, unsure of the gain, throwing the image about 15-16 feet in a room where I can control most of the ambient light. I do have 2 lamps set up on either side of the projector in the back of the room. Is the grey screen ok with this setup or should I go with a white one? Not really sure how the gai works but I think the higher the number the better quality screen. Any help is appriciated.

Jeff