Just remember, copper is a soft metal and bends/dents easily. I would think a plywood backing might give it some support to avoid dents.

Also, I'm pretty sure you have to ground the metal. It's merely a matter of attaching a wire to the copper, and to an electrical ground, but you want to make sure it gets done.

Does grounding also apply to stainless steel backsplashes? Install guides I've read basically say it's fine to use a heavy duty adhesive to stick it to the wall and call it a day.

As far as I know, any metal should have an electrical ground if it is to be used as a counter or bs. The need for a counter ground is more urgent, but it's important for the bs as well. It's easy to forget about this because we are used to using non-conductive materials like tile and stone for these surfaces, but once you substitute metal you have to be sure that a short in your toaster or range isn't going to give someone sitting at the counter or making tea the shock of their lives.

The potential danger is obviously greater for a counter surface (it's a larger surface that you have more contact with), but I hit my bs with my pans when I'm cooking all the time. That's all you need to have an issue.

eam44, are GFCIs not enough to protect against a potential shock?

No, it's not. And grounding a surface is easy enough, I don't know why you wouldn't just in case. It's a matter of running a wire from the bottom of your bs to a ground wire. But I've only read about this stuff, I've never done it. Check out the metalworking forum, or possibly the electrical forum to get info from a pro. While you're at it, check out the copper counters people have DIYed on gardenweb. You'll be able to figure out what adhesive to use, and info on maintenance, etc...

You say the manufacturee "suggest that one install the copper on a separate piece of plywood and then nail the plywood to the sheet rock."

Follow their suggestions.

It will be MUCH easier to smoothly adhere the copper to a sheet of plywood that you can place flat on a workbench than to do it vertically in a small space.

When you cut the plywood, make sure you leave enough room around the edges for the copper to wrap.

Better use copper nails.

HDF is more suitable as a substrate than ply.

24 gauge is very thin, so make sure you use the plywood. You should be able to adhere the plywood to the walls with panel adhesive. That will eliminate the need to nail or screw the wood to the walls. You mention it comes in a roll. Be careful when you unroll it to avoid kinking the copper. You will not be able to get the kinks out after the fact.