I have both. Performance - they are the same from my perspective as long as you have the Pro coil.
You can configure the E-Trac audio tones to almost match the Explorer tones, so that's not an issue.
E-Trac displays and translations are different. They are not difficult to learn, but they are different.
The E-Trac handle is better for your wrist and arm, as the handle angle is different. Takes a little bit to get used to it.
E-Trac has a better pinpointer.
I like the way the quick mask set-up works on the E-Trac better than the iron mask on the SE.
If you read Andy's book, then you can see some of the differences in set-up, features and capabilities.
Good luck - either way you can't go wrong.