I have the device running on Win10, MacOSX and IOS 11.2.1, always via WiFi. Prints excellently and even after a week's break the pictures are of high quality and without "eternal pumping".
The >Quality< can be set on all drivers - as a selection with a slider between Best and Fastest, or Draft-Standard-Optimal. - I could not find an explicit dpi selection in any driver - 2.52 current, firmware PL10HB. - I need the XP-950 for photos, photo cards and thick papers - one of the few that allow "automatic duplex".
For copies (it can't fax) without demands, just select "fast" in the driver. -
I can't say how much this setting saves ink. - For fast and cheap, I have a colour laser; even if the XP-950 prints an A4 photo in standard quality in 20 seconds.