We've flown out of BER around a dozen times this year and last and it has almost always been a pleasant experience.

Certainly nicer than FRA and less stressful than TXL used to be (with security at the gates). Of course it might help that we don't usually travel at peak times.

We found fast track security to be hit and miss, so now prefer to book a (free) time slot through the "BER Runway" system: https://ber.whyline.com/

We've never needed more than a few minutes to get through.