A -3dB point at 30Hz with a minus 10dB at 28Hz, means it doesn't go very deep and the extremely steep roll off of PR subs mean room gain will help very little.
Tom Nousaines test for Sound and Vision Mag, gave a 10% THD distortion figure at 25Hz at only 72dB (At the same frequency BK XLS-300 manages 100dB at only 8% THD) and complained of limited dynamic capability.
That said it is a very small sub and the comments should be viewed against that fact and in a small room where max volume isn't an issue it would probably add some nice low end kick to a modest setup.
The thing is, if you don't mind extending the 12" cube to 13 or 14", it would appear that it's capabilities can be easily surpassed for the same sort of money.
I should qualify that this is based on no personal experience of the PSB, but merely interpreting the results from a proven reliable source.
The HD10's close-miked response, normalized to the level at 80 Hz, indicates that the lower 3-dB point is at 32 Hz and the 6-dB point is at 30 Hz. The upper 3-dB point is at 120 Hz using the LFE input.
Tacked on at the end and almost an afterthought. Not exactly encouraging, IMO.
Go for the XLS300, if you fancy a PR, I'd say