we have a chance to change bikes from a burley duet to a santana visa----will we be upgrading any and how ---we have got to go look at the santana ---we have never ridden one
Have ridden several Burleys and 'tanas, from early models (70s for 'tanas and 80s for Burleys as well as more current models of each brand). Depending on the model/year/components you may notice some differences.
Back in October, I sold a very early Burley Duet (suntour), that I had since new, and bought a '93 Santana Visa. The difference in the frame is monumental! The butted tubes do make a difference. The bike is about 5 lbs lighter and much stiffer laterally. I was happy to get rid of the 27" wheels, and with a coldset of an additional 5mm in the rear spacing (up to 145mm), I was able to go with a nice modern Shimano 9 speed hub. In my case, the best part is that it fits my wife and I perfectly.