I was thinking about this today after my speedometer wire broke. I have to splice it...
The first year I was here, someone DID die on the Bow River pathway after being hit by a speeding cyclist. So I do think it's completely reasonable to enforce a speed limit, given how busy some parts of the trails are becoming.
Calgary's traffic bylaws are very specific that bicycles ARE legal users of the roadways as well as pathways, and have the same rights and responsibilities as car drivers. There have been quite a number of ads and public awareness campaigns about it, and my experience has been that most drivers are good about giving room (and the ones who don't realize they are passing too close, when I catch up to them and politely ask them to be more careful, have all apologized and thanked me for the heads-up). Yes, there are careless drivers and the constant construction is not helping matters, because that adds a lot of distractions, but overall I'm a lot happier cycling here than I was in oh-so-Green Victoria, BC (where the drivers DO aim for you - if they are paying attention to the road at all...)