If I may ask, what were you considerations for having near 100% unit-test coverage even before private beta?
First, we caught bugs (not even regressions) just by writing tests. More importantly, many time when we left code without tests, we found a bug in it later. We're not 100% sure it's been a good investment, but we're 90% sure.
Second, because it wasn't that hard. With the tools available, writing tests that cover all of your code is not too painful.
Third, in private beta we're sure we'll have to change things as we face scaling problems and get failure reports. We wanted to have these tests before we started monkeying around with code.
But you should think heavily about differentiating from Geckoboard. For one I would add some kind of Apple / Android appstore metrics. Geckoboard doesn't have those and I would be glad to pay you if you did.
On a tangential note, our main objective is not differentiating from Geckoboard, it's creating the best online dashboard out there.