Testing has shown that the CTX:
1. With DISC pattern, keeps the TID displayed while the E-Trac loses its TID earlier when unmasking close ferrous-to-non-ferrous. The E-Trac down-averages much more than the CTX (in either open or DISC pattern), which drives the cursor into the DISC area (no audio or display). Thus, the CTX has more stable Fe values when amongst iron soils.
2. The CTX displays a red triangle when the cursor shifts into DISC areas. The E-Trac is mute and has no display cursor. The E-Trac gives no hint there is a possible target under the DISC area.
3. The E-Trac, with Open Screen (no DISC) will give accurate audio on a non-ferrous target adjacant (horizontal to) a ferrous (nail) target at much closer separation than the CTX. That is, the E-Trac in Open Screen unmasks better than the CTX when a nail is perpendicular to the sweep (lengthwise nail is at right-angles to the axis of illumination). This is no small thing - the E-Trac in a field of random iron nails has a better ability to provide a high-tone audio on the adjacent non-ferrous (at closer separation and slightly greater depth) whereas the CTX will give either a null or low-tone (depending upon the pattern you use).
Therefore, if using DISC the E-Trac will lose the non-ferrous target faster due to down-averaging (really up-averaging as values are raised) into the higher Fe values, than the CTX. Otherwise, in Open Screen, the E-Trac still down-average but will still have better unmasking ability.
4. If the nail is Parallel to the sweep (aligned along the coil axis of illumination), while using DISC, the CTX was superior in unmasking ability. Which means the CTX has an advantage over the E-Trac depending upon the nail orientation to the target (when using DISC).
Assume non-ferrous targets are surrounded by nails in random orientation - then at times the E-Trac will unmask better and at other places the CTX will do better. Turning 90-degrees when investigating a target will help allievate the problems for both detectors.
My judgment: the unmasking under field conditions is probably a wash - but the CTX has better TID stability, is a tad deeper, and has better audio bin arrangements that the E-Trac cannot create. These audio bins are a big help when in Open Screen and Combined Mode - an improvement over the E-Trac's TTF and 4TF modes.
The CTX screen is washed out and almost unuseable in sunlight - the E-Trac screen has much better contrast. The CTX is waterproof for wet weather - the E-Trac is not.
Overall, the CTX is really the E-Trac2 (it doesn't deserve new nominclature) and in some ways is slightly better, but no so much that you'd probably miss anything in the field. That is, there is little real-world advantage other than the better ergonomics with the CTX and the ability to define audio bins to provide more intelligent audio with the CTX. The extra cost probably wouldn't justify the slight improvement you'd get (and the washed out screen is an operational problem of concern).
Neither is favorable for finding small jewelry or thin rings (due to the low operating frequency). Neither is particularly light or comfortable to use. Neither one is particularly cheap to own (buy used!). If you can live without the Fe-Co screen (nice, but you'll still need to dig to know what's in the ground), need better sensitivity to low conductors, a lighter machine, then look at other detectors (T2SE, F75SE, AT Pro, Tesoros, Omega, Deus, or some other such detector).