NEX 7 vs EOS M

You said, "on the plus side is the ability no mount and drive all EF/EF-S lenses, although at a dismal focusing speed." I disagree.

"EF and EF-S lenses can be mounted on EF-M bodies via an optional adapter." This adapter might be made by Canon but it will need a glass diopter. There are only 2 native EF-M lenses in existence for the EF-M body.)

http://en.wikipedia.org/wiki/Canon_EF_lens_mount

EF and EFS lenses cannot be used on the NEX. Unless you use a likewise glassed adapter, a decent example not being  available. And probably not worth the trouble.