The Mouse Belly
All right: two things.
When the iMac goes to sleep, the BT devices do not wake it from sleep like the wired ones did. I have to reach around and tap the power button to wake it, then when it does, it will display a new graphic "connection lost" but in what feels like 5 seconds it reestablishes the connection.
Also, the mouse tracking is slower in this mouse. I like to zip around the screen and although the settings are the same, the wired Apple mouse seemed to accelerate faster. I'll see how I adjust.
But, all in all I am very happy!