I tried this as a replacement in my M&K VX-1250 subwoofer. See my review of the 8 ohm version which I also tried (my comments there also apply to this driver.) This 4 ohm driver sounded even better than the 8 ohm version, most likely because the 270 watt M&K amplifier is rated at 4 ohms and this brought out somewhat more more detail.
You won't go wrong with either of these drivers. They both sound great.