Actually according to a few fellow developers over at Microsoft (a few friends of mine so i cant really link to a source) running metro apps in Window has no performance hit, they just render the app like usual but instead of full screen they "emulate" a smaller screen, hence why you have a minimum size of the modern apps. Also this is clearly apparent when developing and debugging apps in Windows 10.
Anyhow kudos to you for know how modernmix did it
Meh, Windows 10 isn't even in Developer Preview yet; but i have to agree Modern 2.0 with that rounded toggles just feels "off". Anyhow the new icons (or well most of them), the new apps (except the toggle) and Cortana looks great