<p>Evaluating the perceived sense of immersion is essential in virtual reality (VR), particularly in training scenarios, to ensure effective skill transfer to real-world applications. With the rise of mixed reality (MR) simulations, balancing virtuality and reality is a key design challenge. Often, comparisons between different setups along the MR continuum might be necessary to identify the most viable option, which maximizes the training potential and user experience. However, existing presence assessment models are frequently insufficient for A/B testing, particularly in MR contexts, as they fail to fully account for the entire MR continuum. This limitation was evident in our pilot study, employing a seek-and-reach task under two conditions-VR and MR-to experimentally validate a modified presence questionnaire for MR applications. The results indicated that the questionnaire failed to distinguish between VR and MR experiences, highlighting the need for a more comprehensive assessment tool. To address this gap, we propose an experimental protocol for validating a new questionnaire designed to assess the sense of immersion across the full MR continuum, based on the Congruence and Plausibility (CaP) model proposed by Latoschik and Wienrich.</p>