I fly an Eclipse 2 and I’ve compared it to a friend of mines original eclipse.

I would say the main difference compared to the original eclipse is that the engine cowl stretches all the way back to the landing gear making it much easier to install the landing gear.
The wing is also placed further back to easier make the proper CG and the aerodynamic counterbalance on the rudder is removed. Other minor changes are a hardly noticeable cosmetic change of chin cowl shape, slightly lower fin, and if I remember correctly a small change of stabiliser placement (a few millimetres up or down).

I don’t think these small changes have any impact on the flying qualities. Mine flies great but I’m assuming the original one does to.

/David