In Canada (Ontario, specifically), is 'CL2' rated cable acceptable for in-wall installation?
Anyone reading this will need to check out their local code requirements, but...

I phoned the city and the electrical safety authority and it turned out for my case that single family dwellings are exempt from requiring fire ratings on in-wall cable, at least for low voltage wiring which I was inquiring about.

This means that, although having fire rated cable (like FT-4 or CL2) in your walls is still obviously a good idea, it was not a code requirement and therefore will pass inspection.

To answer the questions specifically: CL2 is totally fine for my single family dwelling and will pass inspection with no problems at all.

Again... Building code in your area may vary!!



Also worth noting is that I was looking for non-metallic flex conduit to install in the walls to aid future low voltage wire pulls, and the single-family-dwelling exemptions means that if I wanted I could use simple sump pump hose as conduit and it would pass inspection.  Sump pump hose is a very cheap flex conduit (roughly $12 for 25' of 1.25" or 1.5" diameter hose).  I went with a longer coil of "actual" conduit/innerduct with my installation (longer lengths + better bend radius + integrated pull tape + peace of mind), but will be keeping the sump hose in mind for the future.