I have been thinking about getting a Canyon Commuter 4.0 but I am worried about the internal geared belt driven system this bike has. The only ones that come with a pannier rack are the belt driven models. How would it perform on a hilly commute? Is it ideal? I climb about 450 meters every day. I used to do it on a single speed bike so the 8 gears of the Shimano Alfine hub should be enough, but I am worried about the belt.
Yes, the gearing should be fine. from http://www.sheldonbrown.com/nexus8.shtml the lowest ratio is 0.57 which is as low as many mountain bikes.
The belt is actually wider than a metal chain and has longer life, so should be more robust: http://www.conti-drive-system.com/pages/faq/faq_en.html.
But the internal hub has more moving parts, so is slightly less efficient than derailleur based system, meaning you have to pedal a bit harder. But for 450m of climbing, it should be fine.
I commute up some steep hills (20% +) although with only 170m height gain, on an Avanti Inc 2 that is belt drive / Alfine 8 equipped. I've had no issues with water (unlike on a regular chain/derailleur MTB) despite riding in very heavy rain. The bike is nearly 4 years old and is holding up well. There is no sign of wear in the belt, but the hub sometimes slips in 5th gear (the direct drive ratio) which means it might be time to strip it and give it an oil bath. On the plus side with hub gears, you can change gears while stationary, ideal for commuting I find. On the downside, you do have to ease off while shifting if you have an ounce of mechanical sympathy.
I would caution against it, not because of the belt drive, but because of the internal gear hub. I commuted for 2 years on a SRAM IGH. Water always got inside it until it rusted so bad it was useless. When it was cold, the water in the hub would freeze into a block of ice and I'd have to warm it before I could ride. I replaced it with an Alfine 11 and the same thing happened, also after 2 years. In both cases the bikes were parked inside, but would often get wet during my commute.
If you don't ride in the rain, maybe this will be OK. The gearing should be fine for your climbing. But if you pedal hard, you'll hear crunching noises inside the hub. And they're not cheap to replace.