I think you are well aware of the fact that WFP is really the only way to do these, I know you can use extention poles and clean them the trad way too, but you won't do as good a job that way.
Customers have to be educated, print out some info, even print out the health and safety changes for them
(thats a joke by the way, there is a link on one of the forums to the official government site, heavy reading
)
When and if you go over to WFP, get them to at least give it a try for a couple of months.
Tell them that if you have to continue to clean them the trad way, it makes them a 2 man job as you have to have someone footing the ladder, this of course means that to be able tro keep cleaning their windows you would have to increase the price considerably.
Have you seen Shrek 2?
Well if you have, wring your hands like Puss in Boots and adopt his expression of abject innocence and sincerity when dealing with them
You may lose an account or two, but the time taken to clean the windows will more than compensate.
If you only have a few of these houses then it is neither here nor there if youi are taking a little longer to clean them the trad way, unless you are actually in the process of changing over to WFP then just carry on, but slap a quid on your price.
If it is an estate full you have, then that is different, cleaning them the trad way is dropping your income.
Within a few years there will not be many window cleaners working of ladders, I have been given an account on one estate near me (by another guy on here actually) where the only guys that can really do the houses are those with WFP, along with myself there are 2 others cleaning windows on this estate, all with WFP.
Make the change, don't get left behind
Ian