I believe it just may be your eye finds the access points quicker in third person than first, but the third person view does seem to climb mountains better than first person.

Third person. Partially because you can see the overall layout of the terrain better (actually this is one reason I don't much like 1st-person view--no peripheral vision) and partially because I'm used to exploring a lot in MMOs, which are pretty exclusively 3rd-person.

[WTB MMO-style controls for Skyrim... Until then I'm plugging an Xbox controller into my PC]

sure wish acrobatics would return in a dlc