Well, there are two issues to consider here

1. Quality of service: In itself, I have not notice a significant difference in the quality of service in J on whether this is an E90 or Airbus on PLH or select Rapidair Routes (such as YOW-YYZ).

2. Actual J service (eg: Food): As we know, this is where the real difference is. On PLH flights, the food service is different (with no cookies and Ice cream on PLH flights). E90s are also the primary reason why all YOW-YYZ flights have the fruit plate as a breakfast offering, rather than the old omelette. Given their layout (oven in the back) and with only 2 FAs, it is nearly impossible to do a hot meal service on short-haul flights