Going with the info in the blog posts and personal experience I can see why changing to 1080p would be problematic as you'd need to change your time scalars on a hardware level.
However, going with a 720p converter solution is really sub optimal, especially on a digital panel of sorts. You're going to lose crispiness of the display. A true 8-bit retro order of resolution wouldn't pose any problems in that area but since the raster at a system level accounts for HD(+) it would be a waste to downscale from 1200p to 720p. Besides that the downscaling and displaying of a 16:10 to a 16:9 will either ruin the aspect ratio or will impose pillar boxing which is equally detrimental.
I'll be using my newly bought Eizo monitor (that is really intended for graphician work stations, lol) for the occasion so I'm not worried for my personal experience, however for Mega65 to become successful in its targeted niche space (forget mainstream ;)) I urge Mega65 to adopt to 1080p at some point before release. This is due to the fact that the whole monitor industry is in the process of shifting to 1080p. Even Apple ditched their 1200 for 1080p or doubles (Retina), which I regret but it's just the way things are.
Folks @ Mega65, is there maybe something the community can do to help going to 1080p or is there any compelling reason beyond "it's really tough to make it work" you could elaborate on?
My 2 cents...