thanks NJ
i am aware that i should avoid water getting inside the vents and i will be changing everything over at once(tops wfp/trad entrances/some bottom windows).
ive been looking up a fair bit over the years with using trad poles every day.i will probably lose the odd custy over the water issue but hopefully ill pick up more work than i lose! 
dazmond
when i changed over 5 yrs ago, i only lost 1 - old guy, who i did not even bother to try and talk around,
i made the change in stages , all were given a letter out lining system , and what to expect, wet windows etc, i did them a few at a time for a few reasons,
1. you will be slower than trad to begin with,
as you only get 1 chance to impress them , so you do as good a job as you can on first cleans, they WILL check windows after , as they will be unsure how they will dry, from then on they won't check them as closely.
2. you can start with the ones you know will accept it better, then others will see you using system , and accept it better.
these days there are more and more using wfp, so chances are they will have either seen it, or heard about wfp.
once you get 1st cleans out the way, and are confident, you will be flying round your work,
when it comes to winter , every day will still be like a summers day, in as much as you will clean at the same speed in winter as you would in summer ( no more trying like a mad man , to dry leaded in damp cold weather.)
there will be times when you consider changing back, but stick with it , it's worth it
best of luck
daz