Matt, you keep asking about Essence basses; I didn't want to respond since there are others who have more experience with the different models. But maybe this will be of some help.
I have an Essence 4 and Essence 6, both fretted; and I have a fretless 5 string bass with Europa controls. The Essence 4 has been my main bass for almost 8 years and my relationship with it continues to grow.
To me, the 4 and the 6 sound very different. The 6 is of course much heavier and the neck is much more massive and my guess would be that the extra mass probably contributes to some degree to the difference. The 4 has a Maple neck, Maple body and Maple top. The 6 has a Maple neck, Mahogany body and Walnut top. And I think the different body and top woods also contribute to the different sound. The sound of the 6 is much warmer and has more low end support. The 4 has much more attack.
I love the sound of my Essence 4 when the filter is all the way up and the pan is in the middle; it can really sing up the neck in a variety of styles, and down low on the neck sounds great doing slap, rock, blues and more. However, when I roll off the filter, I am not as pleased with the tone; it seems to have more growl than I am often looking for. My experience with my SF-2 and my fretless with Europa controls and some correspondence with others in the group suggests to me that the solution may be the addition of a Q switch. I believe I am correct in saying that the filter in Essence controls has a Q that is always on. Adding a filter switch would give me the option of turning off the boost that the Q provides at the filter frequency, suggesting to me that the sound should be smoother.
You can order a filter switch and install it yourself (or have someone install it for you). I haven't yet because there are other things I would like to do for my bass for which I will have to send it to Mica, if I can ever part with it. (I've been watching for another 4 string so the parting will be easier.)
Now, I have not really focused on this as being a problem with my 6; and as mentioned above and due in large part to the reasons mentioned above, the 6 has a significantly different tone to begin with. But, I do not play my 6 anywhere near as much as my 4 and thus I am just not as intimately familiar with its tone.
It could be that the tone I'm getting when I roll off the filter is influenced by the fact my bass is all Maple. And it could very well be that its just in my head, a matter of taste; after all there are a number of Essence owners in this group and I haven't read anything like this before. (And it could be my ears which over many many years have suffered significant damage due to feedback caused by inadequate soundpersons and overly loud guitar players.)
My fretless 5 with the Europa controls I play even less than my Essence 6. But the additional options of the treble and bass boost/cut switches are very nice.
So; the sound of an Essence is very good to begin with, but my guess is that it can be much enhanced with the inexpensive addition of a Q switch. Europa or Signature controls can add much more, but are also going to cost much more.
If anyone finds any of the above to be off base, please correct me; or if anyone has a differing opinion, suggestions or additions, I welcome those too.