If it's new and made in the last 20 years (lead free), it's a bargain.
I just bought a used water heater tank, with the coil in it. But I had to spend a few hours cleaning it up.
You might not be able to remove the coil without cutting it (it's been installed before final closing of the tank).
The pros of a water tank are that all in/out plugs are already here (for drainage, mash pumping, thermometer, etc.) and if not used can be fitted with plugs (to be used later or not).
That's the one I bought a few days ago, currently undergoing some changes
And it would make no sense to have a water heater tank in brass (it's heavy and average thermal conductivity). You'll have some brass fittings on it, and it's not a problem, they're all food grade anyway (on a water tank)