I bought my EF-S 17-55 f/2.8 IS USM from Hit Camera & Video Ltd in Toronto. Their price was much lower than Vistek's and Henry's, in fact almost identical to the B&H price at the time. As another example , Hit Camera carry the 5D bodies for $300-$500 lower than Henry's and Vistek.
No doubt, there are some benefits in walking into a brick&mortar store which carries equipment demos one is interested in.
However, I challenge you to find any of these lenses on the shelves of any Henry's store: 16-35, 24L, any T/S, 35L, 85L, 135L, 180L, 200L, 300 f/4....etc, etc....not to mention any supertelephotos. And if you happen to see a copy in their store, I bet you a nickel to a doughnut that is a return.