you are much better off going into WFP from a trad background as your understanding of window cleaning is so much greater, one of the problems of going straight into WFP is that learning those trad skills (and there are times when you have to use them) takes infinitely longer, and you are unlikely to ever truly match a skilled trad window cleaner.
For those that are trad and going into WFP, you also realise that there is also a great deal of skill required in the use of WFP if you want to achieve top quality results.
As time passes though, more and more will enter the window cleaning arena directly via the WFP route, and there may well come a time when it is the only route to follow.
Ian