e Reader options for xc soar?

To directly answer the question... yes, we had a problem with a Kobo last year, and I've seen a few go belly up in our club. In my case, it seemed to be very sensitive to sunlight on the unit. I built a high tech heat shield (i.e. piece of cardboard form an Aircraft Spruce Shipping Box, so it was at least aviation grade cardboard) and that seemed to help. My son and I were flying our twin Grob in a local contest, and between the two of us we had 3 instances of TopHat running (1 Kobo, an HTC One, and a Samsung Galaxy). In my "real" glider I fly with a ClearNav. No quesiton the ClearNav is optimized for the type of racing and XC that I do, but the price point on Tophat is pretty nice. With the phones, I just power them on an external USB battery (Anker or equivalent) with the Bluetooth and cellular service turned off. More than adequate for most flights.