RE: 150 meter rule.
I havent tinkered with it in a few months and havent completly sorted it outbut if memory serves using altitude from the pitot gave decent GPS 3D mapping with the Eagletree. I did have to move my pitot all the way out to the wing tip to rid what appeared to befalse readings from pressure created by the propeller/fues??? using you smart phonefor way points or verifying Googleearthcan also be a useful tool. FWIW coming from close in 3D type flying to pattern I have had a problem with 150m +. I feel comfortable at 100 but I fly intermediate so what do I know