Hi Andre,
I own the CJ GAT, and have spoken with a number of people who really like the ET3...i also have owned the ACT 2 and the CJ PV14L, so have about 12+ consecutive years of knowledge of living with CJ. I think the ET3 is a great call, from everything people have told me based on their comparison to the GAT and other CJ preamps. These are people's whose taste i can calibrate.
And as for the CJ GAT, it is the one i chose after considering: Zanden 3000, Shindo Petrus, ARC Anniversary, Wavac PRT-1. OK - i clearly am a tubed guy for preamps and CJ at that!...so i admit my bias!
Coming back to ET3, people have confirmed to me it has very similar sound to GAT in balance...and i will say, having considered CJ ART 3 second hand, ARC and Shindo...i was pleasantly surprised to find the CJ balance to be somewhere in the middle of all of these...whereas by 'stereotype', one might have [mistakenly] assumed it would be in the golden camp. It is much more netural (somewhat like ACT 2)...but far less artificial in the treble (and i loved my ACT 2)...more natural in every respect. Thus you get the sensation of the golden bit from CJ...but without actually having the golden bit added. Very fine balance indeed, and once which i understand ET3 manages in its own way.
Just passing along comments from friends whom i've known for a long time.