The tach and the install are both holding up fine. I haven't had any problem with either, although every once in a while, when at idle, the tach will zoom up to about 3,200 from the idle indication, and then settle back down. It never happens off of idle and I think it's probably some sort of electrical anomaly. Aside from that, functionality is perfect and the water temp gauge is a real plus, especially in our hot-hot-hot South Florida summers.
And while the bracket initially looked a little flimsy, it has held up fine, with just an occasional tightening.