I just checked out the top climber:
I am just pointing out the safety issues I see in a vedors video no less. I agree your equipment should be in good shape. However I looked again at this vedor video and the climber is using a block supported by a shackle- How do you inspect this shackle without climbing the mast- it is impossible (unless you use the internal mast haylard- so why use the external block at all? Surprised a vedor would post such a video with such safety errors.Not my video.
But, having used the ATN Mastclimber, I can say: 1. there's no reason not to rig a backup line - we did, worked fine, but there were two of us there. Alone, I'm not sure how you'd do it; 2. Used the main halyard to go up the stick so unless you haven't maintained that part of your system then given that the main is way more loaded than the 180-odd lbs of the climber in question, you'll be just fine. Any bosun's chair is using a halyard to get up the stick. The difference in the Mastclimber is that one ties off the halyard and rappels up the halyard, rather than hauling the halyard itself up.