Diki: “Oh, and someone that has bought a MoXS is no more a 'power' user of keyboards than someone with an open keyboard (I've heard users of both suck royally! But I've heard a lot of arranger users suck too. Plenty of sucking to go around ). It all depends on HOW WELL the keyboard suits the task, and how difficult the keyboard makes it to achieve the task.”

I think you are finally getting there.
Except that the sucking is more about the user than the machine.
Some people may gravitate to a certain OS and other may not.
Most persons here like and perform well with the Yamaha OS but, there are others like you who like and perform well with the Roland OS (can someone say Mac v. PC).
However, there are some who suck on a Yamaha and a Roland.

And, again no keyboard is 100% perfect so what people do, whether they know or not, is to prioritize what is important to them and make compromises.

The G70 is heavy but because you like the way it operates and the sounds, you compromise and use it any way.
Although the S900 is toy-looking and only have 61 keys, some people compromise and get it because they like the way it operates and the sounds.

Although an open keyboard forces one to get sounds and styles from third parties, some persons compromises because they like the convenience of having their studio and live set-up integrated in one keyboard.

OH and I use a Gem Genesys which has the concept of integration. I can use it in a band, easily tweak sounds, create styles, record audio and use as a OMB with relative ease.

So when I am in the market for a keyboard, naturally I will consider an open keyboard.