I use the FS-5L with my AC-60 and previously used it with my BC-60 Bluescube. The red LED light is great for confirming channel switching and there is a polarity switch to ensure that the light comes on for the appropriate channel.  In the case of my AC-60 I use it to signal that the amp is audible (mute is off).  It uses two AA batteries to power it (the newer model uses 2 AAA batteries).  The batteries last a long time, but I have noticed that when they run low the switch begins to respond intermittently.  The pedal is designed to interlock with other FS series pedals, such as the FS-5U, which helps with the AC-60 because the effect switching uses an unlatched switch.  The downside to this switch is the price and the sharp aluminum corners. If you put this in your gig bag it will be torn to shreds.  The plastic pedal itself can be slippery and is a relatively small surface that gives very little tactile feedback (but it does have the light).