I saw this on Wednesday (26Oct2016 matinee). I wanted to comment on the question of seating, but could not find that link, so please forgive this message's placement.
Regarding whether STAGE seating is a good idea, I think it boils down to whether you want to just VIEW the action or be A PART OF the show. Sitting on-stage, one definitely feels part of the production. The audience on-stage is organically woven into the design, not just an add-in. Definitely more integrated than, say, the Spring Awakening bleachers on-stage. Second choice would be the first row of the regular orchestra, since much happens there also.
The on-stage seating is rather vast, with several different sections. I was surprised that the rest of the orchestra [regular] seating seemed smallish (also given a serpentine platform bisects the orchestra seating). I could not really see the mezz., although there were ramps up to that section from the main stage.
A warning: the entry to the stage involves several (20?) stairs up and down. A man in front of us had two(!) canes and really struggled. If you have mobility issues, please see the House Manager or an usher to find another way to the stage (from back-of-house perhaps).
Some other thoughts: this is a spectacular show, rather than an intellectual night-at-the-theatah. More event than deep drama. The setting was amazing: rather than depending on movable set pieces they relied on the overall design, creating specific environments with lighting and lyrics. The lighting, IMO, was special. Note: if you do not like strobes and intense light (were you freaked out at "Curious Incident ..."?, for example), better skip this one.
One of my pet peeves these days is Sound Design. Often the lyrics--especially--and the music is muddled and flattened (looking at you Waitress). The Sound Design for "Comet" was such a welcome exception: we could hear everything distinctly, quite the achievement with so much going on. Grateful for that.
I agree that they need to work on the Comet, kinda underwhelming. PLEASE no projections, tho. Also the setup for the Comet song (JG) was confusing. WTF is his issue? Hopefully, they can clarify the metaphor of the Comet (foreboding a tragic war?) and make the visual more compelling. They still have a bit of time to work on this, and need to do so.
I hope these comments are helpful to those considering this show.