As a current and frequent user of this form factor (Pico 4, with the top strap, which the Steam Frame will also have as an option, over Virtual Desktop) I can assure you that it's quite comfortable over long periods of time (several hours). Of course it will ultimately depend on the specific design decisions made for this headset, but this all looks really good to me.

Full color passthrough would have been nice though. Not necessarily for XR, but because it's actually quite useful to be able to switch to a view of the world around you with very low friction when using the headset.