I will try this, whilst being wary of Apple innovations. Over 20 years ago, Apple had an image delivery system for pro photographers which was free, easy to use and, above all, uncomplicated. It was secure (well, as much as anything online can be secure), it was fast and it worked seamlessly with Apple Macs. Then, one day, Apple announced without any reason behind it that they were deleting the system. We then had to scramble to (a) download all the myriad image files in the Apple server, which we used as both part-storage and delivery vehicle to clients, and (b) find another delivery source. Luckily for me, I found one locally in Australia built for photographers, and I've been with DPhoto.com ever since. Other colleagues haven't been so lucky.
I'm all for progress and innovation, and Apple is normally a good example of this philosophy, but I will still be wary until Pixelmator gains acceptance and longevity. As I've just bought a new Blad digital back, I'll throw some hi-res images & see what it does - how it compares in speed processing RAW Blad images as opposed to Nikon NEFs. Fun times!