No one would buy a Buchla 281t or other version of that if they wanted a Maths and understood how both worked. The DUSG and the Maths and the 281 and all the other function generators are not similar experiences even if they have similar elements. They don't directly compete with another product in a way that makes the other one. Behringer changed whatever they needed to change to make the price lower, but they're still selling the same experience. Illegal or not, it's still a choice whether that's the kind of business you want to support if you're already buying a boutique niche product.