I previously used a Frequency Division detector coupled to a recorder, then a fairly good cheap detector which enabled time expansion recordings.
The USB microphone (dodotronic 384 Evo) gives much better results. I'd say it's the first time in my life where the sonograms resemble what the book says they should look like! I've always had a good indicator of the peak frequency, and rough call shapes, but rarely as sharp as this.
The high and low frequency of the call is much more accurate with the USB mic.
( Older tech, I got the feeling I could tweak the display when analysing the recordings, and get whatever high and low frequency I wanted!)
The USB mic didn't seem to be picking up harmonics, or much background hiss.
Also seemed to be more sensitive. Lots of Noctules last night, and I picked out a single Daubentons passing thru without any problems, amongst the pipistelles.
I've attached the USB mic to a parabolic reflector, to see what that produces this evening following the same route. This could be ideal, as I could strap a phone or tablet to the handle with a handlebar mount, and not run out of hands.
The android bat detector software was quite powerful, but hung a few times, and was a bit fiddly tapping the screen. Changing to activating recording with the phone volume buttons was a big improvement.