I am not accusing you of intentionally tormenting someone. But it can happen unintentionally.
I don't really see another way through your dilemma other than hiring a tech who mixes the way you want. I am not saying finding the right tech is easy.
Here's another possible piece of the puzzle. Good techs don't intentionally mix in a way that sounds bad. But you may think it sounds bad. The point is good VS bad is subjective. You hate what they like, and they hate what you like
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I would think most good techs care about protecting their reputation. If they think the sound you want is bad, then they are less likely to do what you ask. It might seem like they are tormenting you, but there is not necessarily a conscious intent to torment behind their actions. Rather they are trying to do a good job that they think will build and maintain their reputation. But unfortunately, you are stressed/frustrated because they are not doing what you want them to do.
So you really have two choices...try to force them to do what you want or hire someone who does what you want willingly. Given a choice, I am sure you would choose the second option.
The functional difference between an active bass through a DI, and using a Preamp DI really depends on how you use the controls on the bass and the Preamp DI. The Preamp DI is an extra layer of gain stages and also potentially an extra layer of processing. Some players use fairly aggressive EQ on their bass and then turn around and layer on a lot more EQ with a preamp DI. They also apply even more EQ with their amp. It's generally not a great idea to cascade three stages of heavy EQ IMHO.
I generally run my bass flat with the volume wide open when I am using an amp. I get my basic sound by adjusting the controls on the amp. My DI is typically separate or set to Pre if it comes from the amp. The advantage is I am able to tweak my sound as desired without jacking any of the mixes. During the show I may make subtle adjustments to my bass's tone and pickup blend controls to suit individual songs. Since this sort of change will impact all of the mixes, IMHO it's a good idea to confirm the changes work as expected through the PA during sound check.
I don't generally have any need to use a Preamp DI if I have an amp on stage. With some of my amps I could see the benefit of using an inline EQ pedal, as the tone controls on some amps don't really do what I want. But I would still prefer plugging my bass into a DI before the signal goes to the inline EQ, so the audio tech gets an unprocessed signal
I already explained a situation where I would consider a Preamp DI advantageous.
