[Rover]

So they confirmed that the SA-mount is dead - no more cameras (oddly they say new lenses but that's probably super-cheap to do for them anyway).

Yes, it is super cheap to do. Sigma SA mount is basically Canon EOS with a Pentax bayonet mount. 44mm (like EOS EF), same signals and protocol as Canon EOS. So really just a narrower mount to be screwed on, and you have a SA version.

So, did the Sigma SA mount lenses have troubles focusing on the native cameras like the EF mount versions do (if the general wisdom is to be believed...) with the Canon cameras? There's all manner of talk circulating about Sigma "not fully cracking" the EF mount protocol and whatnot.