I've picked up the Keen's Arroyo II sandals recently, but I'm wondering if they'll be cool enough for my purposes. I'll be traveling though North Africa through June and July where temperatures are typically 83-96 degrees Fahrenheit (28-36°C). I'll be going on occasional treks through more rugged areas, where sandals may not be appropriate for things like hiking or running, but most of my time will be spent in cities interacting with the locals. I'm trying to pack as light as possible, but would this particular line of shoes be a poor choice for my travel plans?
I was actually very curious that you were considering 'sandals' for hiking - a brave man. Until I clicked and realised there was such a thing as Hiking Sandals.
Anyway, I did some research and found an article about when and why hiking sandals can be a bad idea. The credibility seems pretty sound - he actually recommends the Keen range (even has some affiliate links to them), and explains when they have issues.
I think your biggest problem could be sand getting in and causing rubbing. In the cities, you'll likely be fine if you're not carrying a pack too much - I wore closed shoes and socks in ultra-hot, dry climates last year and didn't have much problem - as it's dry the feet don't tend to sweat as much as they would in say, Singapore, where it's humid and hot!