There is gonna be a ton of lag no matter what. I don't think you'll really notice the difference the spectators make.
You've also recommended that we get about 1 sub per 4 man in the roster. I've got about 95 people signed up, and i'm not thrilled at all with the idea of having 15-20 guys just sitting, looking at the server list or doing other stuff. I felt absolutely certain they would at least get to see the game, not idling for 1,5 hours.
It also takes a ton of organization to make sure you get the right guys in every time. Nobody wants to spawn with less soldiers, which means alot of time and energy will be used with simply making sure the right guys get in. Remember, we're talking about ~90 people in a team. That's easily gonna be 5-10 people regularly being switched out, and the simpler it is, the better. (Its not like in a clan match where you say to one guy "You're in next round" and he replies and its no problem. Making sure 5-10 has gotten the message clearly across is no easy job)
Having some people streamline isn't an elegant solution at all. We all know things are much more fun to watch live. With who and how would you even do this?
And to Bulzurs little edit:
With 1,5 hours battle, some people will drop out. That's to be expected, so if you want to be effective, you need substitutes for the whole match.
