I have a neighbor that uses a 60e dish and it works. I have never heard him say that he has problems with rain fade, but then again, it seldom rains here.
Everyone else I know with a Shaw system uses a 75e, myself included. When a strong shower does come up between the dish and the satellites, I have experienced brief periods of outage, but in a general rain (which, again, we don't get much of) the signal is fine.
I have heard that the 60e is a little more difficult to aim, but I personally have no experience with this. I mounted and pointed the 75e dish myself with ease.
All that being said, if you already have the 60e I'd give it a try. If you still have a choice of which dish to use, I'd use the 75e.