Looks like the front-end still needs some polishing. A cursory glance shows a type (My Settings -> Add Alert Contact -> Mobile (SMS) "...that suppor it..." , multiple clicks on the main logo pull up multiple "Loading" messages.

Also, I find it odd that the interface is > 1280px wide(at least it is for me presently). I'm not used to a horizontal scroll on a 13" MBP.

Overall, if it turns up less false positives than Pingdom, I'll be happy.