Brennan, the unfortunate thing, as John said, is that you cannot switch between SACD and CD layers on the fly. You have to stop the disc first. So, it's easiest to compare the beginning of a song on both layers. SACD players have an "SACD/CD" button on the front panel and remote to allow you to switch layers. Just make sure you know which layer you are starting with. Sony SACD players can be set by the user to choose either the CD or SACD layer by default.
For my Sony player, 'C555ES, it takes about 10 seconds all said and done when changing from redbook to SACD or SACD to redbook with a hybrid disc. The machine cannot be playing the CD when performing the changeover.