I think it depends. As an E35K/E50K on Flex and Latitude fares, I've had all sorts of experiences, ranging from being re-booked into a J fare on the next available flight (and getting miles), to being given a middle seat in the second last row of Y. Every time, its out of YYZ heading to western Canada (YEG or YYC) after misconnecting from YUL or YOW.