This is the nonsense from CyclingQuotes.com
"The one-day races have remained popular though and in recent years it has been hard to find a genuine Worlds contender that was not riding either the Vuelta or in Canada even though the Tour of Britain seems to gradually establish itself as a third path. However, things are slightly different in 2016. Held on hilly circuits in the cities of Quebec and Montreal, they are ones for the riders that excel in the Ardennes classics and that makes them less comparable to the Worlds course than it has been the case in recent years. The big sprinters who are the favourites for the rainbow jersey, have little incentive to travel to Canada as they have no chance on the tough courses. Instead, most of them have opted for the Tour of Britain and this will give a different feel to the Canadian classics."
Delusionment there I think. Although the Canadian races have a higher ranking, I don't think they have the same clout. As for the difficultly, the profiles of the two Canadian races are easy compared to ToB. The top sprinters in the ToB are here because it's a good test for them with chances on a few stages - but they've got to work hard to get to Bristol and London to compete well. The crowds are great as well, probably bigger than the 3 weeks of the Vuelta from what I can see - which must be a great spur for the racers.