The interface for Stacking data and Combining By Case in Displayr is not as user-friendly as in Q. In Q, users can drag and drop single or multiple variables at once making it very simple to align variables. In Displayr, this process can be much more difficult when there are changes (e.g., Variable Name, Variable Label, Response List, etc.) to the survey and when there are more than two data sets. An easy-to-use interface for Stacking data and Combining By Case in Displayr would be a major quality-of-life improvement.
Displayr
+ > Data > Data Set > Combine > By Case
+ > Data > Data Set > Stack
Q
Tools > Merge Data Files > Add New Case
Tools > Stack SPSS .sav File...