I have an 159 but not an x159 - so I understand that this is now acrylic instead of metal? I'd be interested to hear your review!
My 159 works really well and is a good pen, but I barely use it because of the weight. I like to post my pens but that's really infeasible balance-wise with the 159's all metal construction. Looks like the x159 is substantially lighter but also marginally shorter when posted.
Post pics and thoughts when you get them??