Stick with it, you'll get there in the end.
There is a steep learning curve, just as when you first started cleaning windows the trad way, it takes time to get the hang of everything and do a decent job.
Don't try and be fast, be patient and thorough.
If you can tag along for a day with an experienced WFP user in your area then you will find this a massive help, there are sure to be a few that are within an hour or 2 from you that will help you out.
The guys from Ionics also run a course too, not expensive and well worth attending....just bear in mind that it to do the job to the standard they are showing does NOT mean you have to buy or use their equipment!!
Domestic work is fine done WFP, not all accounts are a nightmare to deal with, and if there are trikes, BBQ's, garden heaters, tents, shrubbery, paddling pools and god knows what else in the way, well they are also in the way of you using a ladder too.
You have to plan effectively, you work differently with WFP and hoses than you do with ladders.
In general, trad is quicker with regards moving around, and slapping your gear back on your vehicle, but the gains you make on the actual window cleaning by and large more than make up for it.
My best accounts?
Well priced domenstic work, preferably the larger houses, usually stand alone accounts, but even my normal 3 bed semi's pay well, and I certainly could not do them quicker using trad, and like Neil, I've been in this job over 22 years, and I too know me onions!!
Ian