Fraser, I enjoyed both videos very much but as you asked at the start of Part 1 for feedback I will offer my thoughts. 
Perhaps due to the excellent weather my over-riding impression was the scenery. As someone more familiar with the Lake District and the West Coast of Scotland I’ve always held the view the Cairngorm are er… boring, a bit like the Pennines. But in Part 2 that impression was blown out of the water. The view from the summit was impressive.
As for balance I must confess the radio parts went on too long. An option might be to have two versions of the video, the full one with all the QSOs and an abridged version which focuses more on the location.
I suspect you dub the sound on afterwards? It makes for clear audio but it lacks the realism of a live recording - but I know the problem of live recording when the wind is blowing so again it is a balance. Better audio which sounds like it was recorded in a studio or something like a live recording.
But the above are just my reactions. The technique using a GoPro on a stick really works to draw the viewer into the action and give an impression we are on the walk with you. That aspect really works for me.