Frogman,
I had the luxury of having both the ET1 and ET2 in my showroom in the 80's mounted on a variety of turntables along with other top arms of the day such as SME V, Zeta, Alphason, Dynavector, Odyssey, Sumiko The Arm, Goldmund, Syrinx PU2/3, etc
The ET1 had a bloated bass, slower and less tuneful than the ET2.
The ET2 was clearly more transparent than the ET1 by a considerable margin.
The improvements to the ET2 are as follows :
Decoupled Counterweight - This offers 3 advantages.
The decoupled counterweight reduces the horizontal mass
The decoupled counterweight splits the low frequency fundamental resonance, which results in two peaks of lower amplitude, improving the LF performance as demonstrated in Thigpens testing.
The decoupled counterweight provides the capability to tune the decoupling spring to the cartridge.
The maths may be taxing for some, but the Thigpens ET site has documented test results demonstrating the advantage of the decoupled counterweight design. It is incomprehensible as to why any individual would ignore Thigpens test results and convert the ET2 back to the ET1 format in respect of the counterweight, unless their system does not have the resolution to take advantage of this patented decoupled counterweight design, which yields a quicker and more tuneful bass as you have found in your testing.
Adjustable VTA that maintains correct position of the stylus
The tower provides easy adjustment to ensure the level of the horizontal bearing is congruent to the platter surface.
Here is a pic
http://www.eminent-tech.com/history/modelone.jpg