please keep in mind that i am NOT saying that you shouldn't be careful when handling R123. but some people want everyone to think that this stuff is poison. at the end of the day, this refrigerant doesn't require any different handling techniques than any other refrigerant from a safety standpoint, an EPA standpoint or a good practices standpoint. do you need to have lower ppm setpoints for your refrigerant monitors? sure. but that is for long term exposure safety. in the short term (refrigerant handling, spills, etc), you handle R123 the same as any other refrigerant.
Once you go black...you never go back to galvanized.