[puddleglum]

Hey, it's nice to see another fellow Albertan on here. I can only speak from my very limited experience, none of which has been with a Civic. It may just comlicate your decision more, but I hope not.
first, be prepared for a slight drop in mileage with new tires. From what I've read they need a little time to break in.
Next, consider the type of driving you do and the gearing of your car. You don't state what your commute is like. Better gear reduction isn't always a benefit. Also, is the larger tire/rim combo going to be heavier than what you have now?
Softer tread compounds on sport tires are designed for better traction and handling, not better mileage. The tires that have a reputation for the best mileage are poor performers otherwise. (like potenza RE92)
If you do a lot of stop and go in town, added weight will more than offset any gains from gearing. Even on the highway, if the taller gearing takes the engine out of it's most efficient run range, It may hurt. Hopefully you get some response for other Civic owners, but on My Rondo I found that taller/heavier tires hurt my mileage, both city and highway. In town, because of the added weight and on the highway because the added load keeps it from dropping into it's light load fuel reduction mode. In contrast, my Eco does better with my larger summer tires (which are worn out and almost bald by the way). They are about the same weight and that engine benefits from a little lower rpm's. All that to say, each situation is unique and you need to try and identify as many variables as possible. Good luck.