My self adjusters never worked well anyway. Did not seem to keep up with proper adjustments, so I would manually adjust mine every few weeks (it was a daily driver then) to keep them perfect unison.
That was more my reasoning for wanting rear discs than anything to do with power or reliability or parking brake issues. It was for maintenance (or lack thereof) and no longer having to mess with them. And changing pads in just a few minutes, vs a couple of hours of messing about with shoes would be another big bonus!
Paul