I am still using them and really liking them. I do still use my real tortoise on acoustic at home, but at least now I have replacements for them (I gotRedBear to make me some matching ones). I have gone through about 15 of them, but not because they wore out, but because I gave them away to people! I just put in a new order to get my custom picks in Jasper from Dave. For acoustic I think the tone can't be bettered, for electric the tone is good, but you do have other things that influence it too.
The extra heavy is about 2mm, but it is incredibly stiff. I have lights which are around 0.9mm and my acoustic are just over 1mm.
They do wear, but it is very slow, you should easily get 3-6 months out of one (unless you lose it or give it away!).