I received the East 3D Gecko upgrade kit, last fall, and recently I had finally gotten around to tearing down the printer and installing it. In the process, I also installed some RGB lighting, ceramic heat bed, and the Lerdge power-off module kit as well.
The upgrade kit changes the gantry suspension so that it hangs from 4 points, instead of the original 2 points. It also changes the XY gantry, providing a new rail to make things much easier to square up.
I ended up removing the power-off module after it resulted in a blown fuse in the ac input switch – thankfully the blown fuse protected the main board and power supply.
The ceramic bed is a much flatter printing surface – and is supposed to provide much better print adhesion. In practice, I find it works really well, provide that you have the surface perfectly clean and levelled from the start. If either of these things aren’t perfect, you end up with a spaghetti print!
One of the other upgrades I did previously was replacing the stock hotend and extruder with original E3D components.