O wow...I use them too, I love the smoothness it generates. I wish I had more of them though, it's just that they cost so much!!!! Here's a deviation I made with them, if you would want to see. Working on improving my technique... fav.me/d6jwly8
Totally, I buy one once in a while just to fill my collection. I'm standing at about $160 worth, which is quite a lot in my country. I covet my collection (along with my Faber Castel pencil collection) and it's kind of 'hands off' for anyone else.