You don't need LoE3 in Toronto. LoE2 suffices. As to triple pane, this forum is very pro-triple-pane, but I am in the Chicago area and resisted the urging for triple pane from my windows guy and opted for double pane on my Marvin Ultimates. I chose double over triple because of the cost, and also didn't want the windows (casements and sliding patio doors) to be so heavy. I have been very happy with the double pane Marvin Ultimates. Even when the temps are low single digits, I am not getting condensation or any other problems. Having said that, I am careful about setting the humidifier in my house in the winter in order to avoid condensation.
Also, my installer was great. It's all about the installation. You could have the best triple pane window ever made, and if its not installed properly, you'll have problems.
Q