I find that US-based research outfits tend to have a very poor understanding of how the CMHC works, and take views which usually lack explanation or any logical construct.
For instance, it is rare to see the bear-side research outfits acknowledge that CMHC-insured mortgages are essentially government bonds. Sometimes the bank bears attempt to imply that there is widespread fraud in the origination process (evidence of which is scant on an anecdotal basis in Canada). Sometimes they simply fall back on platitudes or things that would have been more applicable to the US style of banking environment where the banks were running, and were burned by large duration gaps in their portfolios -- obviously not applicable to the Canadian banks that do not generally rely on or engage in maturity transformation as a source of revenue.
The most rigorous analysis, IMHO, of the Canadian Schedule 1 banks (not the credit unions which I believe are in serious trouble!), is the willingness of people to bid them up to levels that have now exceeded their valuations in 2008. Something which has not happened for most other sectors of the publicly traded stock market in Canada.