I've been a SoundLab dealer since the late 90's and only know of one case of a failure involving a PX panel, and that was due to shipping damage - specifically, a forklift spearing the crate that the panel was in.
There were two main sources of reliability issues in the past. One was tiny (molecule-scale) microflaws on the inside surface of the insulation material for the stators, which were present in some batches of insulation material and not in others, and which were undetectable in normal testing. That was solved by the supplier manufacturing the insulation material and metal conductor (stator) as one unit using a bonding process that precludes the possibility of any tiny microgaps between the two.
The other main source of reliability problems was something that Roger told me about in confidence so I won't repeat the specifics, but it involved one of the components that played a supporting role not behaving ideally under very humid conditions. That problem had been especially elusive but was finally diagnosed (and easily solved) around the time of the introduction of the PX panels.
Now these aren't the only refinements SoundLab has made which significantly improve the reliability of the PX panels, but they are among the reasons why current-generation SoundLabs have such a good track record in the field.
As for compatibility with Atma-Sphere amps, the new backplates SoundLab introduced in January will give you what used to be MA-2 level performance (or better) with MA-1s, and probably very close to previous MA-1 performance with M-60's.
Obviously being a SoundLab dealer I have a high opinion of their sound quality. When I set out to develop my own line of loudspeakers, I told Roger West that my goal was to build the second-best speakers. I know of no other speaker technology, including what I use, that does so many things so right as the SoundLabs.
Duke
dealer/manufacturer