So you only have one bike that does everything- Hilly rides- Local commuting- Century rides- Tuesday night with the local club for a quick 30 miler at 25mph average.

Then there are the days when You pull it out of the shed- and hear a squeak that is brake rub on the out of true rim- The mates have come round and the rear has a puncture- and the Slight problem you had on the check up ride on saturday evening before the big ride on Sunday has turned into something major and the LBS is shut.

Plenty of reasons for N+XXX so don't even think about the negatives.

Take it the Synapse has been your main ride for a while and there are probably be a few changes you could make if the incentive was there.

And look at the use that you could put the Hillbourne to. That should tell you what components to fit. Personally- if you are happy with Ultegra I would stay with it- but possibly look at the gearing to make it suitable for the future use.- Touring and you will probably be looking at a triple- Heavy touring and still a triple but possibly with 48/36/24 chainrings. One thing I would definitely get sorted though is a Decent set of wheels.

With N+1 you could possibly get your dream bike------Or that may be on the next bike- or the next one.