The changes between -08 and -10 do add clarity (I especially like the simple removal of the word "any"), but I still feel something on forward interoperability would be helpful.  We discussed my LC comments in email, and I understand where the authors and WG are coming from: libraries will move at different velocities, and this format _is_ backwards compatible to 3339.  Still, it gnaws at me that as people start to use these new modifiers, portability and interoperability issues will arise that are perhaps worth noting (given how pervasive 3339 support has become).