Dave,
Thanks for the well reasoned reply. My question then is are most users of these devises aware of the limitations of the construction of the line they use? In my experience most are not. This then brings us to the question of how do we educate. I realize this is another discussion all together!
However, back to topic,, should/can we differentiate between ascent, descent and work positioning? I think we can and should. The forces on the rope are different. Inspection of T.I.P's is different, the end goal is different, the activities performed are different as well as what equipment may or may not be appropriate.
Just as Kevin mistrusts attaching to a toothed, one way ascender (I respect Kevin's opinion on that, I just do not share it). I have similar misgivings in ascending with only one attachment point to the tree/line.
This is why I feel it important to differentiate between the tasks we do to get aloft in trees and work.
In speaking to ascent, where the line has been set from the ground and the climber's goal is to go up. In these cases, redundancy can have many benefits. The tenants of any ascent system should include. The inability of the climber to capsize, the ability to proceed up or down should any equipment failure happen, the inability to fall should one piece of equipment fail. (Naturally if your rope fails you lose, so lets leave that out of the discussion for now as catastrophic, spontaneous line failures are rare) these seem simple and necessary precautions in my mind.
On the flip side once the climber has ascended, secured in the canopy and closely inspected the T.I.P. and is preparing to descend and work. The systems must change and hence the equipment, techniques and most importantly the mindset.
Do you see what I am getting at? To lump one system into the "climb" category is oversimplified and fallacious. For years we have used but one method to ascend, work, descend. It worked but with flaws.
Now we have much more knowledge, techniques and "thinking" at our disposal, yet I feel some still "lump" too much into one basket looking for the holy grail. In the process, clear thinking, open minds and in the end safety may be compromised.
Again I will look forward to hearing everyone's response.
Tony