RWD - the other factor is the amount of cushioning, I have Mizuno Mirage and Fastwitch shoes that are both 4mm drop - but theres a lot more padding in the Mirages. The Mirage have 21mm padding in the forefoot, the Fastwitch have only 15mm (so the heel padding is 21+4 and 15+4). There is a noticeable difference between the two even when standing still.
The Cumulus has 22mm padding in the forefoot, so you may find the Kanadia is less than this (sorry can't confirm as they not listed on my favourite reference site).