We didn't go with Rackspace/Akamai specifically because they don't have a custom origin pull - pushing your assets somewhere else is at the very least a pain, and if you have images or video that is dynamically sized based on the URL it's pretty much a nonstarter.
We looked at Cloudfront but they don't have an Australian distribution point. In the end we went with EdgeCast (via GoGrid).
Originally we were with Voxel, but they've had a couple network issues in the past month (result of DDoS attacks I think).
They are cheaper through resellers like GoGrid. I believe it is competitive with Cloudfront.
As far as speed, they were among the best as far as we were able to test. There are lots of variables involved though that make it kind of hard to compare - how long things stay in the cache at the edge vs. your traffic patterns, etc.
Yep, it can be a big annoyance to say the least. I'm using Rackspace in this case because I only need to constantly export the same 5,000 to 10,000 data files. My individual embed file sizes are in the low KBs, so AWS was going to murder me on the per transaction costs (low file size, high volume).
We looked at Cloudfront but they don't have an Australian distribution point. In the end we went with EdgeCast (via GoGrid).
Originally we were with Voxel, but they've had a couple network issues in the past month (result of DDoS attacks I think).