@pataphysician: i think that sort of thing depends more on the sim card's placement on the device than a technical requirement that the cell portion of the device be shut down. Most of the time they can be shutdown by software anyway to simulate a 'power cycle' if it's required by the sim at all.

Of course I may just be talking out of my backend here, but if you care that much about a 1 minute planned downtime, you can try hooking the device up to external power before you turn off the cell radio (without powering down the device) and swap the sim card.