Any views on which will absorb the shocks better on a rigid bike? I have a set of low rise Eastons on the SS but am thinking of doing a swap with the other bike, which has flat Ti bars. Dimensions are pretty much equal, both 25.4mm by about 580 wide.

Should I spend half an hour swapping them or stop faffing about and do for a ride?

Go for a ride.

I'd go carbon, I reckon it'll have more flex in with regards bars where as I reckon a ti frame will be more comfy than carbon. That's why I have ti frame with carbon bars and post. Not sure why I have come to this conclusion but it works fur me.

Changing your grips would make more difference to 'comfort' than any change in frame/bar material. I'm sorry but that's true.