a foot deep... usually in spaces that are not easy to use because buried by the transom. on the typical Vee drive boat, the steering gear sits under the anchor locker, aft seats with little access in hard to use space.
on aft cabin styled boat, the steering gear fits in cabinetry, behind the bed, etc... taking almost no usuable space.
engines are smaller. yes, probably true
trannies are absent ? not really... look at the size of the coupler and ips in the above pics... it's bigger than a tranny and stuffing box. darn.. you made me go down and measure

as big as my DDs maybe be, the distance between the rear of the engine BLOCK and the ER aft bulkhead is 30".. and again these old allison trannies as abig as they get. I see at least the same distance in the above picture.
A critical benefit of IPS is moving the ER aft, allowing builders to better organize and use living spaces, not really the pure size of the power package.
Hulls colors ? they're fine up north... forget it down here. I have a black stripe on my hull, you can barely touch it in the afternoon. i can't imagine the whole hull being dark... i wonder how much extra insulation they have to use to allow the ACs to cool the cabin.
as to maintenance, better not have an oh s..t moment or the scar will be far more visible... it's a great deal for dealers and fiberglass guys
