BTW, for the mica shift (and other techniques) you need a really sharp blade. Seems the Nu-Blades I've bought recently have dulled really quickly. Is it them or me? Anyone else had this problem? Know of a better blade or source for them?

I just love mica shift! All I have is Donna Kato's blades & they seem fine. But I only use them for tissue-thin slicing like mokume gane or canes. For thicker slicing, like cutting up blocks of clay or cutting sheets into pieces, I use those replacement "snap-off" blades and wallpaper scraper blades. They are cheaper and it does not matter if they are not so sharp for that type of work.