Well, if we need individual BAMs then they get a DAC each, but for the majority of shows with paired projectors left/right, they can share a DAC.But really? 2 lasers on 1 FB3? How do you set individual bam zones for projectors?
If 1 projector fails, it takes the second one with it.
And why would one projector stop if the other goes down? I think you're perhaps making too many assumptions, certainly with regard to daisy chaining. If you lose 2 projectors when 1 goes down you have only yourself to blame in my opinion.
Ultimately, were money no object, we'd all have 1 DAC per projector - but if that were the case, we wouldn't be debating why people probably won't be dumping their FB3's in their droves to re-kit with FB4's. Some may well do that, but it'll be the big companies, not the small guys like me running 10 projectors or so.
I don't use TCP LAN based extender, so no I can't use it with my existing gear without changing the extender. Or running another cat5 run. The point I'm making is about it not fitting specifically with my infrastructure. YMMVOf course you can use it alongside existing gear.
Just as an example, you could run an Ethernet LAN TCP based USB extender from the front of house to the stage, then do a split between the usb hub and the FB4's.