I had good results with the Tetenal kits. Pushing one stop and re-using three times were no problem. Their usefulness went way down for me when they stopped selling the 500ml versions.

Nick, I'm pretty sure JD Photochem sells their own 'line' of E6 kits. I just bought one of their C-41 kits but haven't yet had a chance to use it. The instructions are a little lacking but they filled the details in by e-mail when asked. It may be worth a try. Shipping to Toronto from the West Island (Montreal) is pretty quick.