Cheers Ali.
I agree that it's probably unwise to tempt any further performance headaches by using 4k maps ingame.
I guess I'm interested in trying out a photographic collage/layering approach here as what turned me off originally about the CloD maps was the hand painted feel. Is there any other reason (apart from the insane amount of time this would take to do properly within the guidelines of the current layouts) that you would advise against this approach?