  Tree-based model editors and hybrid graphical-textual model editors have
advantages and limitations when editing domain models. Data is displayed
hierarchically in tree-based model editors, whereas hybrid graphical-textual
model editors capture high-level domain concepts graphically and low-level
domain details textually. We conducted an empirical user study with 22
participants to evaluate the implicit assumption of system modellers that
hybrid notations are superior, and to investigate the tradeoffs between the
default EMF-based tree model editor and a Sirius/Xtext-based hybrid model
editor. The results of the user study indicate that users largely prefer the
hybrid editor and are more confident with hybrid notations for understanding
the meaning of conditions. Furthermore, we found that the tree editor provided
superior performance for analysing ordered lists of model elements, whereas
activities requiring the comprehension or modelling of complex conditions were
carried out faster through the hybrid editor.
