I am at the ideal weight for my height. six feet two and 197 pounds and I have no problem with the Speedmaster as a ONE UP touring machine. Its ideal for one rider and his or her gear.
Adding my wife and then packing for her as well would just be too much weight and would detract from the bikes performance.
Our bikes lack the necessary grunt for a full two up and lots of gear long distance rides.
Its not that they wont do two up ....they just cant compete with a larger displacement metric touring bike in the 1300 Cc plus range for two up riding.
I suppose that those who have the big bore see some improvement.
If I wanted to spend significant amounts of time touring for two I would purchase a different bike with more displacement and practicality for that purpose.
Other than that the COOL factor of the twin cylinder Triumph is unmatched by anything else on the road today.