I have personally owned a Tigra mount, bought via LondonCyclist's shop, a few years ago, it weathered the usual Plymouth downpours incredibly well, although I upgraded to a Garmin Edge 510 in May before an event, saving the weight of carrying an additional external battery to keep the iPhone charged.
If you have the 4/4S, I'd happily part with my Tigra mount, as it's now gaining dust.
I have the box, and the mount etc, and I can vouch for it's worthiness, never had any problems when hitting potholes (Plymouth is plagued with them) as well as uneven roads.