I have found a nice, free and open-source online DMN-editor that can be used as a good functionality-benchmark for bpmn.io/dmn. It is Drools’ Business Central Workbench (installation for non IT-people is hell).
But now they put it ready-to-use on the cloud here:
(ok, it supports also bpmn, however I’m more into DMN )
As far as I can see, it supports DMN 100% and is compatible with declab.
So you can test the DMN models created in the editor for completeness and consistency.
AND since the handling of decision tables is not as convenient as in bpmn.io you can even edit some details in the decision tables with bpmn.io (ignore all error-messages) and still test the model on declab.
I’d say this is a good example for the compability of DMN between three tools.
Keep up the good work