Not sure where the info came from, but Rane mixers do not blow away Pioneer and especially do not blow away A&H mixers. A&H are some of the best sounding mixers on the market.
The Rane 68 is a disaster, a lot of people who bought them hated them, horrible layout, too confusing and buttons breaking a lot. I am not saying Rane is bad, they make awesome mixers, The MP24 was flagship for clubs and mobile for a long time but the Pioneers in my opinion just offer more on their mixers effects wise and the sound quality is the same, if not better.
A&H DB4 is one of my favorite mixers but too much for me to spend, Any of the cheaper A&H I cannot get a happy combo with being I love rotary and effects
so as far as the last question, i personally think the Xone92 will sound better but will you notice the difference between that and an 850? I doubt it
If you are into effects, the xone92 does not have any except for a filter, so the DJM850 wins in the effects area
