The recent/current ArcGIS Earth Beta had a user forum accessible from the Beta pages.
However, even though the welcome to ArcGIS Pro 1.2 Beta said "bookmark the ArcGIS Pro 1.2 beta site (link below). This will be your main portal for submitting feedback", when I go to that page it says "Please submit your feedback through Esri Technical Support (support.esri.com/en)".
When I go to support.esri.com/en it says "My Support is moving to My Esri We are moving Support information to My Esri. Everything currently available on My Support will soon move to the Support tab within My Esri."
I've noticed at least one ArcGIS Pro 1.2 Beta question on GeoNet, so while we are waiting for the Support tab within My Esri to be ready, is there any advice on whether posting ArcGIS Pro 1.2 Beta questions to GeoNet is permitted?