I bet we could probably learn a lot about heavy bikes from those guys who drive bicycle taxis in various parts of the world. I am no specially skilled rider
but I have a tandem bike and I give rides to a number of people who are otherwise unable to peddle. i have a place in the frame where I ask them to
keep their feet so as to not interfere with the cranks going round and round. Hard to put into words but you do indeed gain a unique perspective.
I also ride my tandem solo which is unique.... I say it feels like a bicycle limousine. One thing I have to say i like a little bit is the fact that the front wheel steering is far less twitchy and might be more steady if I was riding hands off .... which I would never do.