My test would be as follows:
1. Set the password to lock after X min (common for those of use on corp exchange accounts)
2. Turn the device off.
3. Call the device and try and answer right away.

With the old version it seemed like all hell broke loose as everything tried to launch on wakeup. This caused lockups on some calls or a delay in button response when trying to answer.

I like what I see in the screen shots.. looking sharp.

One suggestion that would IF POSSIBLE. If you are going to offer the option to turn off the screen but keep the device running, could you see if you can alter how the LEDs flash so the user knows the device is not in sleep mode?