I've asked myself the same question. I am still not ready to recommend Xeomin use to my patients for a few reasons. I should also point out that I am in the process of completing a very large study comparing Botox, Dysport and Xeomin using only the highest quality research (a meta-analysis).
Like all businesses, there is a lot of marketing. Xeomin's claims to fame are #1 you dont need to refrigerate it and #2 there is less risk of allergies. After reviewing over 20,000 patients in a number of randomized studies, there are no reports of allergies with botox. Yes, there are reports of this happening in other series but it is extremely rare thus I dont believe that Xeomin offers any advantage in this regard. At this point, there is absolutely no evidence one is better than the other. Its just marketing based on "theory."
Also, Botox is such a popular brand now, people ask for it by name. I think many people are nervous about trying a product that has been on the market for a few years versus one that has been around over 15 years. I tend to use Botox cause I know it works, its safe and people are happy with the results.
Also, there is evidence that Xeomin may not last as long as Botox. Now, this is controversial but hopefully the study I am doing will answer this question. At this time, there is no reason to believe one lasts longer than the other, however....time will tell.
Finally, one of the "benefits" of Xeomin is that it is considered a more purified version of the active component of the toxin. Basically, botulinum toxin contains an active component (that results in the key effect) and some other proteins. Xeomin removed these proteins and thus the notion that there is less of a risk of allergy as some believe the allergy risk is associated with these proteins. However, there is another side to the story. Some people suggest that these proteins are important for making the medication work better, thus some believe this is the reason why Botox may last longer, it keeps some of these "extra" proteins that may have a role in improving its effect. Who knows, maby these proteins are required for things like, finding its way into the nerve it is going to effect.
Wheww...Long winded I know, but its a complicated topic and one I find interesting.
I think I'll end by saying, I dont know what the right answer is, it may turn out there is no difference between products. But as a physician, my goal is to treat people with a medication that I believe is the safest and most effective available. At this point, Botox is that product. Perhaps my opinion will change once more evidence is out there, but for now, I continue to recommend Botox.