Why would you want to shut off your valve when it's already paired? Your transmitter goes into a sleep mode if there is no pressure change for 5 minutes. Once you begin breathing/purge on your regulator, your transmitter wakes up and starts sending data.
You can always force it to re-sync by turning off your valve completely and then turning it back on. The transmitter will now select a new code. Your Vytec must be in "SETC" mode to pair the new code.
You can also manually erase the store code by pressing twice on the TIME" button, then press the "PLAN" button follow by pressing the "MODE" button. This will erase the stored code and starts displaying "SETC", which allows a new code to be paired.
Most newbies including myself make the mistake of turning ON the valve before turning ON the Vytec, which causes sync issues. Always turn on your Vytec first before turning on the valve.
Sorry, but I'll have to disagree with you on this point. Just because there are workarounds to problems doesn't make it a good system. The wireless system on Suunto's is TERRIBLE. With Oceanic and Uwatec, it's a permanent pairing. Set it up when you first buy the system, and you're done until you purposely break the pairing (after going through a number of menus to do so), or until the computer/transmitter finally dies. It's truly set-it-and-forget-it. The fact that special procedures have to be followed to keep a Suunto computer paired with it's transmitter is just a bad idea. (Plus, other people sometimes turn your tanks on and off, especially in a vacation/boat setting, and sometimes you need to walk out of range of your tank... stuff happens in the real world.)
I've just read far too many complaints about Suunto's pairing system to cut them slack on this one. All the other wireless AI manufacturers seem to have no problem on this point, just Suunto.