For me, it would be the choice between making it more lifesized, or more view. I would choose the more lifesize with the 42 inch job and mount that puppy same as my CRT is now, directly behind and touching the base of my wheel
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But then, they don't look so good up close (can see the pixels with it a foot away...), so perhaps I would go with the triple...
Well, then there is my choice. Since I like to replicate my display as being the windscreen, and the distance between my display and my wheel as the dash area as best I can, I would probably change my decision and go with the triple head-2-go.