Interesting thread.
I have used RO/DI cold water Pure Freedom system since starting in 2009. I've never added anything to the tank, nor would I.
I use TFR (Evan's TSR 100 or 200) on green uPVC and most first cleans, and G101 on fly sh*t (the only thing i've found that does the job) in either hand-sprayers or from a trolley, depending on size of job. The TFR is necessary to soften the algae and ground in dirt on first-cleans, but unnecessary on any future cleans, if regular.
I weighed up moving to hot - and couldn't justify the set up and running costs for the additional speed it would undoubtedly give me mainly on first cleans only.
I saw an improvement in ease of clean (not necessarily speed) when Gardiners brought out the dual trim Supalite - it moved across the glass easier than the single trim, so was easier on the arms and shoulders.
Additives. Necessary, nay essential, for bad first cleans and connies (unless you want to be there for double the time); totally unnecessary imho on most regular maintenance cleans. I use TFR on my van to soften road film and rinse with tap water. However most windows are not the same as my van which like yours is sprayed directly with all sorts of horrid stuff, unless by a busy road with spray when I accept an additive might help
if added in sufficient volume to the water.
I do wonder if guys are rinsing with water with an additive whether the residue (of which there must be some) will form a microscopic, slightly sticky layer on the glass to which dirt dust and pollen will stick more readily (look at the top of your Fairy bottle). This alone would stop me from using any additive in my tank.
Finally, ppm versus ppb debate a while back, i'll say this. If a window is totally clear at say 004 or 005 ppm (it is, i've tested it on several occasions by accident
)why would it be necessary to move to a ppb system?