HP310 works great once you have worked out the wrinkles:

1) don't let it run flat
2) sort out a way to charge / power it in flight
3) tape over the battery cover switch
4) put tape beside the on switch to prevent it being turned on accidently
in storage.
5) get your airspace and turnpoints sorted

Screen is good, XCsoar522 is good. I carry two for use in club duo fixed
to canopy with standard suction mount. Secondary power with 3500mah L-ion
battery connected with custom usb cable.

Jim

ps: use seeyou for comps in my own glider though.