This afternoon I went trail running on snow covered trails of Mt Royal. I was impressed by level of difficulty winter adds: stairs are no longer stairs, the terrain becomes uneven and unstable, and you have to make sure you don't drift to far to the edge when your running the crest at the top. In other words Mt. Royal becomes a bit more of a technical run (as opposed to just fun). If this appeals to you, then the only thing I'd caution is that you be careful not to trample the x-country ski trails... I like to ski as well.