Smush Pro quality

Hi there.

We are looking at using Smush Pro for http://www.wonderbold.com, but they have said they used a compression tool in the past and the quality was reduced too much.

So my question is: if we try it and they are unhappy, how easy it is to switch it off, and use the original server versions of the images – pre-Smushed. What's the process for doing that?