I lived in the Waterloo area for 15 years and I don't think there is any place in the KW area where you can try them out. Your best bet is Vistek in Toronto. I know they have them and they would let you look at them in the store. Good luck.
In addition to Steve's suggestion of trying Vistek:
Jeff at Photocreative in Mississauga, though I don't know what he has in stock. He's a big Leica enthusiast.
If you're interested in any Zeiss rangefinder glass, contact Rob Skeoch in Burlington at http://www.rangefinderstore.com/ and be sure to tell him I sent you. He has a Zeiss trial/rental option available.
A bit out of the way, but I've been happy with my dealings with Jean at Leica Boutique in Montreal http://rangefinder.camtecphoto.com/ I have only dealt with him online/email thus far.
Where did I try before buying? I didn't... I just bought the camera used, then bought a few Zeiss lenses from Rob to get my feet wet. I figured if I didn't like it, I could always resell the gear with minimal loss.
Thanks for the suggestions. I did already contact Rob, but he has no actual Leica lenses.
For unnamed reasons, I'm only interested in 'coded' Leica lenses. I'm not actually looking to buy right now, but need to perform some tests for a project I'm working on.
I know stores don't like it when you want to try without buying, but the shop I checked at seemed willing to help in this regard if they had any open/used one on hand.
@HerbChong, thanks for the insight. I guess that leaves me with finding somebody willing to let me try/rent theirs.
So, probably not very likely, but is there anybody nearby willing to help me out?
PM me if so and we can discuss.
I can second Ron's recommendation for Camtec in Montreal. My dealings with Jean have also been online, for Voigtlander and Zeiss SLR lenses. I hope to meet him in person next week.
There a store in Yorkville in Toronto called setidel studios I think that specializes in used lenses. Never been in there but the were open to letting me try. That's a possibility.