I've tried the x series, they work good but feel a bit to flimsy. I went with the 5.85m because it's like a brick, very solid. It also has a high gpm even though it's a lower psi which I like. The hose wind up is also better. Every wind up reel washer I've used that has it up top (especially bolted to the handle) always breaks loose some how.
As far as uses, the stock vario wand and a foam canon by mtm is all you need. I do also have a right angle for under carriages.
DRIVER - The Karcher websites (as there seems to be various ones out there) offer confusing information. They make the X-Series appear to be the newest units they offer. Some don't even show the 5.85M as being available anymore. In addition, there's the 5.54 and 5.74 in the X-series. Though the physical size is different and the color of the plastics is different, the unit appear to be the same by spec. WHAT is the difference. Why is the 5.85M hard to find as available?
Do you have a link to the MTM foam canon you mentioned?
I think I'm getting this narrowed down now.