Man, you guys are truly incredible with the info! Looks like its gonna be a fun time! When re-charging from cans, I assume you just take it off when you feel you are close and weigh it to verify how much has been put in?
Something about using Cans and "Planning on evacuating/vacuuming/dying the system this weekend to see what crops up" is just not right, seems you are planning on venting to atmosphere. Not good or legal.