[Erwin]

Google has this thing which lets you essentially choose a location (and browser) and run a test with output from the page speed addon: http://www.webpagetest.org/

I'm using Cloudfront with the origin option for a subset of our users. I've found a few clients with so restrictive or broken firewall rules that I had to add an option to default to getting the files from the source if users come from network X or Y. While cloudfront lets you download the log files, you get one S3 object per edge location per 15 minutes or something like that, so 1000s per day, which made things difficult to troubleshoot (I suspect the problem with one user was partial cache due to Apache's deflate sending responses as chunked encoding as default and Amazon's origin spider sometime dropping such connections).