Cycling Weekly recently reviewed 18 different types of wheels and heres what they said about the Spinergy Stealth PBO's:

'Ever since the original REV-X and S'Pox wheels, Spinergy has continued its technological innovations.  Like the Zipps an aluminium braking surface is bonded to the carbon structure, maintaining all weather braking ability.  Marmite looks come courtesy of the PBO spokes: Polyphenylene Bensobisoxazole fibres are wrapped with a UV proof layer with each spoke weighing half that of a steel spoke.  Own-Branded hubs use large diameter bearings, and with free-hub bodies readily available, service-ability  shouldnt be an issue.  Sprinting stiffness is good - if not exceptional.  The flexible spokes mean small undulations in the road's surface don't bounce the rims around therefore they track very well.  Their forte, however, is carrying speed, and on rolling terrain the deep aero rim and momentum make for wheels that just keep spinning.'

Cycling Weekly 9/10