Whilst the design and build quality of the PV1 are beyond reproach, unless you have the need for a sub with exceptionally clean upper bass because you have
very small satellite speakers, then the PV1 is actually bettered (unfortunately, by quite a margin) by the likes of the BK-XLS-200 for £290.
The PV1's main problems are that it was designed to answer a number of engineering problems that aren't actually an issue in subs of a comparable size or performance.
Opposed drivers to cancel vibration? A well made sub is quite capable of providing enough mass to render the moving mass of it's driver an irrelevance.
Spherical cabinet to cope pressure induced resonance? Any well engineered sub of a similar size has cabinet dimensions too small to resonate within the sub bass frequencies.
If it were twice the volume and sported 10" drivers, then we'd have something worth talking about, but in reality, it doesn't actually offer anything other than a style based argument over B&W's own ASW-675 for considerably less money, even at the £700 you've found it for.
FWIW, it's been seen closer to £500 (ex-demo) and in the light of the above, it's still of dubious audio value. If you're only comfortable buying from a dealer and £700 is the budget, then on performance grounds, I'd take a much closer look at REL's T-1.
Russell
PS. The PV1 would stuff the Coda regardless.