i have also read ( on a non-cannabis gardening site) that clones lose vigour the more clone generations they are from a "real" plant...ferst few i would assume is less noticable, but if your talking 10-20 times is gonna be messed up.

i guess thats why people have mother plants, otherwise you could just take cuttings from established vegging clones and repeat the process each cycle and have a perpetual grow thats much simpler.