I just looked at Alex's diagram again and noticed one difference between his technique, and that of the Voyager's Handbook. The connection between anchors in Alex's description is rope, and that in the VH (and CW) is chain and shackles. There is a rope on the Danforth, but it is only used for retrieving the danforth after the main is secure.
Long time ago, I used a chain also, and stopped using it, because first it was more weight I had to pull, remeber main anchor the motor pulls, the first, Alex does.... to attach and remove was a pain in the neck (I just do a quick bowline, which is fast, easy, secure, easy to remove and helps if you don't have time), because I needed to attach the shackle ( right name??), pulling anchor was slippery, and storing was messy.
If it was a permanent mooring, yes, for the time I am anchored 3 to 4 days, the rope is fine..Its not the floating rope, ok??
By the way, I am very aware of the 45º Double anchor, but here with the boat swinging twice a day from east to west, the anchors, if not set at exact lenghts (difficult to do), start approaching each other, as one holds one drags etc. and end up being worse, as that arrangement here ends up in a tangled mess. BY EXPERIENCE...