Having recently driven the Mrs. vRS I have noticed a squeak accompanied by a knock when changing up gears and also when coming on and off the throttle when cruising at a constant speed. It also feels like a split second delay when pressing the accelorator pedal and it reacting at the wheels.

My initial thoughts are a worn bush, possibly in the dogbone mount. Does anybody else have any theories on this or am I, surprisingly, digging in the right area?

I'd say your assumptions are correct - this used to happen on my old Bora - I think it's a common fault on the Fab, the original bushes ain't up to much by all accounts...

Likewise; this sounds likea typical description of engine shunt.