Ya, that is probably the more common one, stopping at 32nd ave. But Remax lists Highwood:
http://www.remaxcentral.ab.ca/innercity-calgary/
And McKnight/JLB makes sense as a delimiter. It's about 5km to downtown, which is about 1/3rd of the city radius to the north. When you look to the south Glenmore is around 6km from downtown and Sarcee is about 6km to the west.
Heck, Forest Lawn is included at over 7km, and I wouldn't personally consider anything past Deerfoot "inner city". Same with Bowness at 10km away. If Bowness and Forrest Lawn are inner city, so is Highwood, dagnammit!