Just been having my first play around with Argo, it's looking very good. I hope you don't mind me pointing out a few things as I notice them...
When importing things from other project files it is great that layer information is now also imported. However, I did notice that this will always create new layers, even if there are existing layers in the project with the same name, so you end up with duplicate layers named the same which is confusing. Would it be possible for the software to look for identically named layers and simply place the imported objects onto those where present? I guess there might be situations that you don't want this to happen so maybe there could be an option to merge layers or create new layers with slightly different name, like 'Name (imported)'.
Also, a more minor point, in Polar when I right clicked to create a new layer, layer set, plot etc. the new item was immediately selected and ready for me to type in a name, whereas in Argo the Layer/Layer Set folder remains as the selected line so it's a couple of extra clicks before I can name the new item. Strangely, for new plots the new item is highlighted but not ready for typing. I think the Polar behaviour is preferable.