most comparators ARE opamps.While you can use an opamp as a comparator, they're really not designed to be run open-loop.
it is a comparator so why do you care about "bandwidth" at all? it is meaningless for a comparator.Bandwidth suffers quite a bit,
that's what comparators do. if anything, they may use positive feedback to push up the speed and get them into saturation deeper and sooner.and the outputs spend nearly all their time in saturation,
deep saturation -> LOWER power dissipation. that's how switching transistors / mosfets can handle lots of current.leading to high power dissipation and heating.
I don't even know what "constant saturation" is.Their open-collector outputs are designed to be operated in constant saturation.