SIM Card stay active after changing phone?

I have a few different phones and depending on the day and what I have to do, I may use one phone versus another. It's real simple and only takes a couple seconds to update the ESN online and then do a *228 to activate. Here's my question, I got the Bionic yesterday and I told the sales rep of this routine and he told me I can't do that with the Bionic because of the sim card. He said once the phone is deactivated, the sim dies and cannot be reactivated and in order to reactivate it, I would have to come in for a new sim each time. He was like, no big deal, they are free, just come in when you need one. Of course he would not give a few sims at the time I purchased the Bionic. Does anyone know if there is any truth to this about the sim not being able to be reactivated?