The present paper describes an empirical user study intended to compare the programming efficiency of our proposed domain-specific language versus a mainstream event language when it comes to modify multimodal interactions. By concerted use of observations, interviews, and standardized questionnaires, we managed to measure the completion rates, completion time, code testing effort, and perceived difficulty of the programming tasks along with the perceived usability and perceived learnability of the programming tool supporting our proposed language. Based on this experience, we propose some guidelines for designing comparative user studies of programming languages. The paper also discusses the considerations we took into account when designing a multimodal interaction description language that intends to be well regarded by its users.