Roff - I agree about the GNS5780 turning itself on in the bag. I fixed it by clamping it face down against my kneepad (which has an elastic strap.
But in actual use I've had no bother at all with it - it picks up a lock quickly and the iPad links immediately.
The real problem with most cheaper GPS units is sunlight readablility, and the ones which are better in that respect are ££££'s.
The iPad is good enough for me, most of the time, certainly better than the budget Aware units which are hopeless in my aircraft.