Here is a quick history of the XE Series
The XE Series line of helicopters all share the same fuselage, rotor head, tail rotor and mechanics, and in a hover, basically have the same feel, responsiveness and stability. However, the differences between the different models is pretty substantial.
XEL The XEL was the first "fuselaged" model of the Mosquito Air to be built and was debuted in 2004, which both are FAA Part103 ultralight legal.
XE The XE is simply a registered version of the 60hp XEL. So if you have a PPL, you can count your flight time as rotary in your log book while working on your rotary add-on, and you can fill the fuel tank all the way up. Lol!
XE3 Feeling the need for more power, CFX then came out with the XE3 which was a 85hp, 3 cylinder version of the 2-stroke/2 cylinder/air cooled MZ202 used in the XEL and XE. They were somewhat problematic and was eventually discontinued.
XET After trying to make the XE3 work for a period of time, CFX finally pulled the plug and in true fashion of a DIY mentality, hit the mark for the need for smooth, reliable and abundant power and came out with the XET, which is considered CFX's flagship model.
XE285 The XE285 is being labeled as its work horse as it brings the price back down a bit from the XET while drastically improving the power and reliability over the earlier MZ engines models. Discontinued in April 2021 and replaced with the XE290.
XE290 The XE290 is the latest version and is an improvement over the XE285 with an automatic fuel mapping ECU, improved cooling, improved exhaust and a larger charging capacity.