the Randonneur collaboration bike was in my possession (it has now been shipped to its owner), for about a month I alternated between riding it and my own Rivendell in attempts to compare them.
When I mention the very idea of comparing these bikes I tend to get completely polarised reactions. To some they look identical: lugged frames, 650B wheels, wide tires, fenders, dynamo lighting, dropbars and classic handlebar bags. Can there possibly be significant differences in how they ride? To others, the bicycles are so obviously different in terms of geometry and tubing, that a comparison seems equally absurd: Of course they will be radically different!
The blueish bike is a one-off collaboration between Royal H. Cycles and myself. Built as a classic randonneuring frame, it is made using skinny, somewhat flexible tubing with fairly steep angles, moderate length chainstays, and low trail. The Randonneur is supposed to be lighter, faster and more responsive than a touring bike, yet still comfortable. The low trail geometry is considered to be optimal for carrying a front load, but overall the bike is not meant to be heavily loaded.
[Edited to add: The difference between these bicycles as shown is 6lb. The Randonneur weighs 26lb and the Sam Hillborne 31lb.]
The difference in tubing is immediately apparent, both when looking at the bikes in person and when picking them up by the top tubes - I can close my hand around the Randonneur's top tube much easier. This made the Randonneur easier for me to pick up, carry around when necessary, and take in and out of the house. As for how the tubing and other differences translate into ride quality, it is difficult to say. The Randonneur is a faster bike, though modestly so. It is also less fatiguing and perhaps a wee bit cushier over bumps. I can feel the frame and fork flex as I ride, but not too much. And I would certainly not attempt to do this on the Randonneur - I think the frame might bend in half.