  We explore the information which proposed matterwave interferometry
experiments with large test masses can provide about parameterizable extensions
to quantum mechanics, such as have been proposed to explain the apparent
quantum to classical transition. Specifically, we consider a matterwave
near-field Talbot interferometer and Continuous Spontaneous Localisation (CSL).
Using Bayesian inference we compute the effect of decoherence mechanisms
including pressure and blackbody radiation, find estimates for the number of
measurements required, and provide a procedure for optimal choice of
experimental control variables. We show that in a MAQRO like experiment it is
possible to reach masses of $\sim10^9\,\text{u}$ and we quantify the bounds
which can be placed on CSL. These specific results can be used to inform
experimental design and the general approach can be applied to other
parameterizable models.
