Joe...I have both and use them both. The DFX is more balanced and seems lighter to swing. E-Trac, once you set it up, goes deep and can sniff out coins a tad better in trash since the ID accuracy, in my opinion, is a bit better. I like the Conductive and Ferrous number system. The signagraph of the DFX isn't a slouch either and if you are accustomed to it, trash becomes a minium.
I do like the fact that you can use the DFX in 15kHz mode for dry sand gold hunting. It is more sensitive to smaller gold than the E-Trac in that mode.
Both hunt the salt water beaches very well. Found gold with both of them. I feel the E-Trac is a bit deeper than the DFX on the beach, but you can swing the DFX quicker and cover more ground.
The stock coil on the E-Trac is a very good coil, but I also have the Sunray X-8 and X-5 coils, and those smaller coils work very well in trashy areas. The smaller 5.3 concentric on the DFX pin points better...both small coils recovery speed is very fast if set up correctly. I think the DFX small coil is a bit easier to use but not as deep on silver. For small gold in parks and in dry sand areas, the 5.3 in Prospecting mode, set up right, will trump the E-Trac by a wide margin.
My opinion is, these 2 detectors compliment each other very well, and even though the DFX is 10+ years of age, to me it is still a top line unit. Not sure if you are going to sell the DFX to get the E-Trac, but if you are going to get and E-Trac as well as keep the DFX, I don't think it would be a waste. There are a lot of applications such as deep silver hunting, hunting in trash and iron, that the E-Trac does better at.
My 2 cents.