[Soundy]

Physically swapping the tank isn't difficult... or shouldn't be, if the piping was done right (some idiot hard-piped straight into ours without using any thread-on fittings). With an electric tank it's pretty straightforward to turn off the breaker and change over the wiring.

With a gas tank, you really want a qualified gas pipefitter so you're sure the piping is done right and there are no gas leaks. But in theory, you could turn off the gas to the tank, do the swap yourself, then just bring in the gasfitter to hook it up.