I've been using a iPad Gen1 for almost a year in the LC and it works awesome. Motion X GPS HD is the best $2.99 I've spent in a very long time. I was going to buy a Garmin and bought the iPad insetad, very happy. The extra screen real-estate for viewing maps alone is worth it.
The glare can be bad but I've only found it annoying in a couple situations. I would say 98% of the time it's a non-issue and I can successfully use the iPad for Nav.
P.S. I bought the Pro-Clip iPad mount you are using at first because it was the first on the market. However I quickly found out why, it sucks. The mount holds the iPad too loose for my tastes when bouncing around offroad. Onroad I'm sure it's fine. I use the RAM mount instead and there is absolutely no way it's coming out on it's own. I've never had it come loose in the worst offroad conditions.