It's the same for me as Dazmond, I've never used or seen WFP except for Germans using WFP on com work. It's only an option for my Brit custies here anyway. It's not the cost factor either, my carpet machines cost alot more than WFP setups.
Just think about this though. When it gets that far in UK, that 99% of window cleaners are WFP. There is an estate of lets say 2000 houses, 6 WC's clean there, 5 are WFP and 1 is trad, who woulld have the advantage for winning custies? And before all the WFP guys say hang him,

It's not the amount of work the trad guy can manage, he can employ too, just like WFP guys can. Has the trad guy got a better chance of getting more custies than the WFP guys? Because people prefer trad to WFP? What do you think?