This isn't really valid. You cannot compare apples to oranges. Having 71,000 of one thing that you trade in for 53,000 of something else does not result in a 25% loss of value.
I realized after I wrote this that it is impossible to calculate because it depends on the currency rates when exchanging back to CAD. Oops.
This is an interesting discussion. You're right -- currency rates can only be relative.
My thinking, perhaps not articulated very well, is that currency rates, like the stock market, are cyclical. If you look at the history of CAD to USD, it is veering towards a low point now. That's not to say that it can't get any lower -- but historically, it is currently close to one of the three lowest dips in the past 60 years. This fact, combined with the fact that US markets are at an all-time high, make me hesitant to buy. I would rather wait a while until the cycles are aligned in a more advantageous way. This is not to say that I will find the height of the CAD dollar, or the lowest point of the US market, but based on history of both, this does not seem like a great time for Canadians to be buying US stocks.
Yes, this sounds like market timing. I'm not saying that the stars are guaranteed to align on these two variables to my advantage. But these facts, and knowing their cyclical natures, make me hesitant to buy at the moment.
That said -- I am not an index investor, so I DO look for value stock purchases that could potentially be US equities. I do not rule them out entirely just because the CAD is low. For example a few weeks ago I purchased some US energy stocks while the dollar was at about 80 cents. Who's to say how that purchase will turn out, but for me, there seemed to be value there. I am always on the lookout for value, and it's challenging to see this when a low CAD / high US stock market align themselves.