Electrostat - M-L; Quad or Soundlab - reliable

What is your definition of reliable? Electrostatic speakers will require the panels to be replaced, much like tubes, but longer lasting. My opinion is (take ML for example) that the panels are very good for 5 years and typically get replaced in the 7-10 year neighborhood. It is my impression, like with tubes, that people don't notice so much the reduction in performance as the panels start to weaken and that is why they typically stay on a bit longer than they should. This being said, the panels aren't really that expensive.

I will not tell you what is the best of the speakers in terms of performance as you seem to have a pretty good handle on this. As for the Quads, I sense there are only certain models that really hold resale value and seem to move fairly quickly.

I think its simple. If you want to own stats, its most like owning tubes. The stats by nature have a life expectancy (as to capacitors in your amps, tubes in your equipment, sorrounds in some drivers). If you know you have a product that has a component that has a life expectancy and that part fails at the expected life cycle, that is not a reliability issue. That is maintenance. You know your tires on your car are good for only so many miles. As your tires wear (beyond a certain level) their performance levels drop. I think this is also true of both stats and tubes.