We bought this to support our two Mackie SRM450 v1s and treated it to two outings over the weekend.
It was excellent in a small, grubby, 200 capacity rock venue and enhanced the low end - though with the volume much past "twelve o'clock" we did experience a degree of feedback. Really needed the extra punch and the dB 615 Sub delivered.
The second gig was a quieter affair at an old fashioned social club. Although we could have coped without it, it added some roundness to the overall sound even at low volume.
Easy to set up and very importantly, relatively lightweight. Nice to have a sub that doesn't require two people to move it!