With a creative approach I think you can make anything work. I have heard my acoustic through my Super Reverb sound great, and also plugged an electric into an acoustic sound and liked that sound too.

Jon is correct though, it can be tough to get one amp to do both sadly as the speakers and preamps are built differently to handle the characteristics of the instrument. I would not suggest micing an acoustic with an SM57. That's a dynamic mic that won't sound right.

Your best approach is to get a pickup in your acoustic, along with a feedback buster that fits in your sound hole to prevent any feedback. From there you can use one amp for both if you have too.

Good luck!

- Douglas