I read the design article. I have no problem with ki disappearing. Psionics and Ki were always internally focused magic to me any way (except for the external gems and a few other things). I glanced at the playtest. It looks interesting.
I really don't like that some classes can buy AC (armor, and then take feats to increase damage or do other things) but that a class like this may need to take a feat to boost AC. I'm no "balance" expert, but it seems to me that this class could pale at higher levels partly because of this. This is also an advantage in finding magic weapons, as opposed to applying rituals to your body. I can imagine, however, how a monk could practice and internally focus his body/mind to recreate the effect of a magic item somehow. I'll have to think about this.