I guess this calls for my "infamous" sheep story. The most difficult situation I have come across was looking at Bighorn Sheep in Rocky Mountain National Park in Colorado. You are at the bottom of a steep canyon and the sheep are high above you on rocky ledges. When the sun is over you you are almost looking into the sun to see the sheep. I had liked my Swarovski Habicht's 8x30 because the on-axis view is great but that day I tried to use them to see the sheep above me and the whole FOV was totally covered with flare. I tried the Canon 10x42 IS-L's which I fortunately had in the truck. I could easily see the sheep with very little flare. The Habicht's went on Ebay the next day never to return. The Habicht's were a good friend but they let me down when I really needed them. I think looking up at steep angles with the sun overhead is obviously one of the hardest situations you will ever come across.
Your Canons will be even more flare resistant if lens hoods are fitted.
I've been very pleased with these:
They weigh very little, are cosmetically unobtrusive and are also protective in foul weather.