I used to be a landscape gardener before I became a window cleaner.
The guy who got me into window cleaning had to spend a considerable period of time persuading me that winodw clenaing would be beneficial to me, financially in particular but for other reasons too.
Anyway, in them days ladders and trad was what was happening and have to admit the figure you're talking that you earn now is less than what I was doing 10 years ago off a ladder.
Im WFP now, have been for 8 months, I have NEVER looked back, ever. For me, and its just my opinion, based on my experience, is that WFP is superior generally to trad, if you wish to start window cleaning, learn trad, but gear up for WFP.