I would like to know what joint configuration was being welded here? PAW's main advantage is seen in high volume repetitive production welds. Mainly on cylindrical products. pyman4407 states that his contractors wish to use the process because GMAW is hard in corners?
Both processes have quite bulky end torches and the PAW end set up require's quite a large diameter orifice and maybe a separate wire feeding nozzle as well, so I feel that the use of PAW process over GMAW would have limited or no benefits if access was the major concern. Depending on joint and material thickness, I would not immediately see any speed advantage over a properly utilised and set up'ed GMAW machine either, other than as Al stated, PAW is nearly always automated to some extent, so if PAW was to replace a manual welder for instance, maybe with time and enough production weld's completed , some saving in time could be seen. But with the high initial cost and setup time, it wouldn't be quick.
Either way, I would also reiterate both Brent and Al's thoughts regarding acceptance of a qualified WPSs
Al, modern PAW machines can use 'Keyhole' technique and also what we in the UK call 'Melt Mode' where additional filler wire is added as well. This is used for thicknesses beyond what can be keyholed.
http://www.youtube.com/watch?v=jo376zPns8I