I love the silver tip! It's the first I've heard of it.
I've got some comfrey growing around the property I work at, interspersed with clover and radish. They got started a little late in the season but I'm just looking for chop and drop cover crops at the moment. I'm hoping for two but will be happy with one harvest.
I've heard that comfrey spreads like crazy and can take over, have you had any problems with that, or does chopping and dropping before it goes to seed keep it from spreading?
RE: What I used to condition my soil the organic way - Started to do (Back to Eden method in my garden) Working great!