can't the normal (low) resolutions just be scaled up 5 times (to 1600x1000) and then displayed with a border instead of scaling up to 1920x1200 and killing 1080p compatibility?
to be honest i am not really interested in the REAL hires mode anyway, and i really wonder who might use that. i think the normal low res modes are perfectly fine, it should only be possible to display those cleanly on a hires (1080p) display instead of letting the TV upscale that for you (with unpredictable results)...