Basically, anything one writes about this topic has to be simplified. There is always more detail. Lots to figure out. Easy to get stuff wrong.
One of the reasons I have kept the adjustable binding on the ski (and I use both demo and Schizos in different situations) rather than switch is that I've found that I want the same binding, with its own peculiarities, including height, rather than to switch to another model or brand that will usually feel different, including with best mount point. For example, Tyrolia has made basically two different adjustable or demo bindings over recent years, one with tall stack height, one with much lower. To me, the lower one feels cheap and rickety, unpleasant to ski on - but it is lower, close to the fixed binding height. The really tall one used to be called the AT (All Types) demo. I only use it when I want, in effect, the 10 mm extra height of a plate under the binding, and on the ski. The Marker demos, in contrast, have in general been the same or closer to the height of the fixed binding version, so better if one wanted to switch to fixed. To complicate things further, most of the binding companies have often made available a different demo binding for rental and demo fleets (wholesale use) than the one they will sell retail, and the one they sell retail is often not available for shops to order at all, or it is in such limited supply that it's a bear to get a hold of, except through a more high volume shop that has a lot of pull with the brands. But often, seems like, the wholesale demo binding is better made, built to withstand a lot more use/abuse for the sake of lower shop maintenance, I gather.
My solution to this has been to identify the demo bindings I like for certain purposes, and buy those on ebay in advance, or through shops when they get rid of demo skis and bindings at the end of the season. And also to go through a high volume shop when there is another demo binding I want. This has required making the connections to do this, and using ongoing strategies to stockpile what I plan to use.