Absolutely understood that you don’t mean it that way!
I’m not myself involved in the formulation of the energy drinks but have some background in many materials used, including sodium benzoate. As it happens I reviewed benzyl benzoate derivatives extensively some while ago, out of interest in possibly using it for its solubilizing abilities for certain actives (this did not go into any product, however.)
Although it provides you no information just to tell you my conclusions from then, I found the literature to very well support safety of benzoic acid derivatives and benzoic acid itself up to some amount, but with a certain limit, as is true for so many things. (All things cause harm at some point.)
But for specific information, first I’m not sure what your specific cause of concern is and so I’ll address what seems the most popular objection (not that that will necessarily be related at all to your objection.)
It’s claimed that sodium benzoate in combination with certain food dyes was associated with (usually more loosely and incorrectly stated as “promoted” or “caused”) ADD in children. The original source material for the claim is Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial - The Lancet .
It does not however show causation or even much if at all support it. A first key thing to consider when evaluating the study is something that I went on about at far too much length recently, and so will refrain from doing so again, is what “statistical significance” means.
If data is “statistically significant” to say p = 0.05, or 5%, that does NOT mean that there is a 95% chance that there was a real cause, different than random fluctuation, behind the measurement. It doesn’t say anything at all about that question. It is saying that where there is nothing but chance involved, with the amount of variation that was seen then 5% of the time a measurement this big will appear by chance!
So what happens when tens of thousands of studies are done per year, each studying many different variables? Huge numbers of instances where random fluctuation alone generates data which is “statistically significant” but not caused.
So there’s a big difference between data being statistically significant, and being likely or not to have been from a real cause. One wants to look at more than just “statistical significance” of an odd thing that was looked at, with no prior in vivo indication of problem and no later such indication either. It can well raise interest but says about nothing about probability of being true.
Particularly where, as here, the data has to be looked at one way, but not another, to reach “statistical significance.”
A good review of this study is at Assessment of the results of the study by McCann et al. (2007) on the effect of some colours and sodium benzoate on children’s behaviour  - Scientific Opinion of the Panel on Food Additives, Flavourings, Processing Aids and Food Contact Materials (AFC) | EFSA
(BTW, EFSA is a lot more serious about safety than FDA is. They’re not at all reluctant to ban or sharply limit materials, and do it all the time. And I find their analysis here sound, and have never found an analysis of theirs I found poor.)
On a more basic level, the study only examined effect of combination of certain food colors with sodium benzoate. It never examined sodium benzoate in absence of the food colors, or for that matter the food colors in absence of sodium benzoate.
So that study has little to say about sodium benzoate safety. As opinion, without corroborating data it can well just be yet another of thousands of results that turn up every year from chance fluctuation and easy standards for p values.
With regards to other human and animal in vivo studies, none have found any problem until quite high doses. Human use has been studied past 500 mg/day. While I’m not apprised of the amount in any Biotest product, the amount will be far, far below that.
Sodium benzoate is, incidentally, when in solution as in a drink absolutely equivalent to benzoic acid plus sodium. On dissociation in aqueous solution, there’s no telling whether the chloride and benzoate ions came from sodium benzoate, or came from benzoic acid and another sodium source. Absolutely equivalent.
So it’s completely correct to evaluate oral sodium benzoate according to information one has on benzoic acid.
So what of benzoic acid? A modern chemical which our systems for which our systems have no adapation?
Not at all. Reportedly (from http://www.inchem.org/documents/cicads/cicads/cicad26.htm#SubSectionNumber:5.3.2 ):
Benzoic acid occurs naturally in free and bound form in many
plant and animal species. It is a common metabolite in plants and
organisms (Hegnauer, 1992). Appreciable amounts have been found in gum
benzoin (around 20%) and most berries (around 0.05%) (Budavari et al.,
1996). For example, ripe fruits of several Vaccinium species (e.g.,
cranberry, V. vitis idaea; bilberry, V. macrocarpon) contain as
much as 300-1300 mg free benzoic acid per kg fruit (Hegnauer, 1966).
That’s a lot in cranberries!
Sodium benzoate is a nature-identical ingredient once dissolved in solution, as it is in the products. Not that all nature-identical things are safe, but it seems this material is being branded on various health sites as unnatural – “Why don’t they use natural preservatives?” in some sources – when it’s as natural as any replacement they might want. (Or if preferred, when in the dry form it’s a salt of natural material, and when in the drink is absolutely indistinguishable: it’s the same benzoate ion either way.)
Because, as mentioned, not being a formulator of the energy drinks I don’t have inside knowledge on them, but as for myself I see extensive body of favorable safety data, natural occurrence of benzoic acid in high amount in some healthful food, no possible toxicological difference between sodium benzoate and benzoic acid, and no human or animal data against it other than a study I find dubious on combination of certain food colors with sodium benzoate in children with ADD. So myself I don’t worry about it nor if I were asked would I advise there’s reason to make a change, but I understand views vary.
That said, I don’t have any information on whether thought has been given to replacement. I have no doubt it would be replaced instantly if we thought it harmful.