I have a feeling that this isn't going to work out for them... it's a lot of work to drag one line around a tree, keeping it from snagging up on stuff and trying to keep good rope angles and a clear path for the rope. Using two lines, it is NOT twice as much work. It's about four times as much work. I regularly climb with multiple lines, all of which I can set from the ground, but the price isn't a little bit more work to keep a couple of climb lines with me... it's a LOT more work. In my case, I'm not on a production schedule, and the great work positioning makes it worthwhile. But, that's not the case for most climbers.
The worst thing about this whole notion of dual systems is that I'm not convinced it will increase safety at all. I've personally never seen any data for tree work that would lead anyone to believe it addresses the biggest killers... lack of attention to what you're doing, stupid mistakes and decreased attention to the details when you're tired and getting cranky.
I saw one article that indicated that falling out of a bucket truck or lift was MUCH more common than a safety line or equipment failure. The whole thing smells of a "make some rules, whether they actually will make a difference or not" attempt to look like they're making an effort to reduce injuries and deaths, without any real research into the most likely things to cause them. I know that's human nature, when you're put in a position to address the problems, to at least try to do something. Really, though... this problem needs a lot of research and analytical reasoning to solve, not a quick-fix regulation.
Personally, I've found that the more stuff you have to deal with while trying to work, the more likely you are to get sloppy and make an innocent, but dangerous, mistake. If two or three of those things are what is holding you up in the tree, that can get pretty scary.
