I just got the Sfb 500.4 a week ago. It sounds just as good and as loud as the Nvx vad 4 I was running bridged to a pair of Godfather 8s. I’ll venture to say that the Sfb has a little less distortion at full tilt. My Sfb is now powering two Sundown neo v3 6.5s as well as the Godfathers. Not much time to experiment yet, but what I like so far is: 1 ohm stable, 2 ohm bridgeable, clip indicator, 1/0 inputs and smaller size. It seems very versatile to my future additions. I heard on a YouTube vid that it has bandpass filters but I can’t confirm that, as I use my HU’s crossover.
hope this helps.