When you use a Waterfed pole you need to scrub the Windows back and forth twice then rinse. It takes some practice but with that many windows you'll be a pro after that. Make sure you wash the window frames too or else it will drip dirty water on the Windows.

Waterfed pole is the way to go , here's my advice. Step 1. Wash the whole frame twice, Pay attention to the top of the frame especially if the window opens. If it has vents you will have to flip the brush to give them a good rinse as these hold a lot of muck. Step 2. Wash the window glass from top to bottom twice. Pay attention to the top and bottom seals as you'll have cobwebs and spiders top and the bottom will hold all the muck. Step 3. Brush side to side from top to bottom the whole window once. Step 4. Rince the whole window. This is my way to clean with a water fed pole and i don't have any problems or complaints. It mite sound alot todo but as you get the hang of it this will take you about 1 minute an average window after the first clean. Thanks Andrews cleaning services

are you using a DI system with this pole ?

If so what one are yall the happiest with ?

I agree with Chris and Andrew. The specific steps may be a tad different, but when you get the hang of it, it is such an enormous time saver most of the time.
The decision to use a simple DI system or an RO/DI depends on the tds of the water supply you will be using. I think everyone has their magic number, but when your tds starts getting well up into the 100's RO/DI will be more economical in the long haul even if the initial outlay is greater. If you only do windows this way occasionally and prefer convenience and portability over economy you can use just DI if the tds isn't sky-high. Too high and you'll burn through your resin before the job is done and need to get your tank readied again.

Using a waterfed pole is a good option as it helps you save money and it is much safer because you do not need ladders and you are working mostly from ground.