I finally found time to learn how to upgrade my firmware by coming down with the flu... Sitting at my computer for hours was about all I could manage.
I now have Marlin Version 2.1.2.5 running on my M2E. Mine printer is a 2917 version, with the Z-stop at the bottom, 24V power supply, and the Geeetech LCD display/controller. I'd like to get the MakerGear bootscreen working, and I've converted the old Marlin 1.0 graphics format to be compatible with 2.x. I haven't sorted out how to turn off he Marlin bootscreen, and replace it with the MakerGear one. Hopefully that won't have to wait until I get sick again.
The main feature I wanted was Linear Advance, so I'm studying how that works and the calibration process. I use several different types of filament, and I need to come up with the best "K" value for each one.