Hi from Auckland New Zealand,

I am selling my old 2004 Sportsman 500 because it is an age where I am absolutely tipping money into it .... That said it is a robust machine - Love the transmission, no changing forward gears at all.

What do I replace it with?

I am on a perfectly flat 5 acre block, no stress there for any machine. The ground is peat so maximum mud depth during winter is about 4 inches..... again no stress.

I use the current machine for mowing (slashing?), harrowing, smoothing a sand covered dressage arena, spraying (Volume of water can be varied to meet what ever the new bike can handle) and sometimes use a small trailer with a standard car tow ball hitch.

Tell me about the CF400

Is it reliable? Is it easy to maintain? Is it easy to service?

I dont know what I dont know so I do not know what to ask you all. I am worried about Chinese quality!

I have a 2020 Cforce400 but only use it for recreational riding and not to work on a farm.  I take care of it but I do ride it hard and not baby it.   It has been an ok machine but since it is my first atv I cannot compare it with anything else.  The normal service is pretty easy with a couple of basic tools and just a bit of mechanical ability.  There is however on the service manual a call to check the valve spacing every 1000 kilometers which seems to be a CFmoto thing only.  I have change the oil, air filter, belt and one way bearing myself (don't worry it was not the machines fault, I killed the belt and bearing for just bad use). I have added a rear mounted winch and also made a small trailer with the same hitch a ball system to just move stuff around. 
The radiator fan died pretty soon after delivery and was replaced under warranty.  Also not sure what happened but the 4wd stopped working and again was fixed by the dealer with no issues ever since.
Hope this helos and If you have any specific questions just let me know.