I recently have started playing ES2 again with a buddy of mine and we agreed that it would be cool if I could observe his space battles and vice versa. Space combat is by far the most graphically impressive part of this game, so being able to spectate and see more of the glorious ship models that Amplitude has created would IMO be lots of fun. 

I understand that having someone spectate your combat would give away information about your ship configurations, so I was thinking this would be only be possible if the combatant invited other players to spectate. If both combatants are humans, then they would both have to give permission to allow spectators. Perhaps there could be an option to invite spectators in the advanced combat screen, where you could choose who to invite. 

I have no idea how difficult this would be to implement, so in my ignorance I will assume it can't be too hard :)

Is this something anyone else would be interested in? 

The interest for this might be a bit niche.  It's not a terrible idea; it's just that games take such a long time already and waiting on someone to watch a space battle eats into an already prodigious time investment.  How much moreso when it's not even their own battle?

I'm not entirely opposed to the idea, especially given the point that learning ship loadouts is a somewhat strategic advantage; I just think it'll be hard to justify it to players given how long a game normally takes.