I think that by and large my price structure stays the same, though in truth it has lowered on georgian work because of the sheer speed of doing them with WFP compared to trad.
Another point to consider is that few will be able to earn as much trad on georgian work as on windows that can be squeegeed...you simply cannot charge enough doing them trad to compare favourably with squeegee work, but with WFP there is hardly any difference in the time taken to clean a georgian window as there is a normal casement window.
Prior to WFP my prices for georgian work were far higher than they would be for squeegee work, but as a georgian window takes at the very very least 3 times as long to clean than a similar sized squeegee window.
But now as there is hardly any difference in time taken due to using WFP I unconsciously price such work not much more expensively than ordinary casement windows!

I think it is hard to justify increasing your overall price due to WFP, most of us who changed over to WFP were probably oversubscribed with work when Trad anyway, ergo you now have the capability of getting all your work done on time, with less effort and shorter hours, which of course means that your overall turnover will have increased accordingly.
Ian