Oh, that "covertible" (HA!) looks SWEET! The reason you don't want to "ride" the rollator is because it is not designed to be bearing the full weight of an adult while being pushed. Also, its center of gravity is different, so it is less likely to tip.

As for the deconditioning issue....it really isn't an issue if you have "planned" exercise periods in your day. This is where the wheelchair or convertible would be ideal! Just head down the street, or through the mall or whatever and go as far as you can. If you get tired, sit and ride. Of course, you would need to have a person with you to assist. Having the planned exercise would take the stress off the times you go out, and you could just be pushed without worry about deconditioning.