I'm amazed it's not better known. (Of course, the USA had to send an emergency repair crew to their own Skylab station when a bit fell off during launch...)
Re station-to-station transfers: Mir and Salyut 7 both had the same orbital inclinations (probably deliberately) of 51.5°; Mir's apoapsis was about 360km, Salyut 7's was about 250km. So a transfer would be relatively cheap. The vehicle was a Soyuz T only had about 320m/s of delta-V, which was also needed for rendezvous and deorbit, so it would have to be.
I think this was the only station-to-station transfer ever done. It was probably only feasible because they were in the same orbital plane.
(Although I'm a little surprised they didn't build Mir using Salyut-7 as a core module. Even if they ditched the module later as it wore out, it'd provide power, attitude control and automated docking.)
According to the article this was indeed the only station-to-station transfer, and although very cool I am not sure exactly why would you do it except for some emergency or for building up a new station out of parts from others like you suggested.
Do you have any idea what use would there be for a s-to-s transfer? I'm guessing it's more expensive and dangerous than launching a specific mission from Earth, so the use would be limited. Maybe to test some emergency procedure a-la Gravity (the movie)?
It would be really cool if there was some other big space station so that this would be something to think about... but oh well, I guess having the ISS will have to suffice for now.... It's not like I have the money to build my own unfortunately :(
Re station-to-station transfers: Mir and Salyut 7 both had the same orbital inclinations (probably deliberately) of 51.5°; Mir's apoapsis was about 360km, Salyut 7's was about 250km. So a transfer would be relatively cheap. The vehicle was a Soyuz T only had about 320m/s of delta-V, which was also needed for rendezvous and deorbit, so it would have to be.
I think this was the only station-to-station transfer ever done. It was probably only feasible because they were in the same orbital plane.
(Although I'm a little surprised they didn't build Mir using Salyut-7 as a core module. Even if they ditched the module later as it wore out, it'd provide power, attitude control and automated docking.)