Hi Trask,
I am a new Glowroot user and I would like to start by saying thank you for this great tool.  I am amazed by how simple and useful it is. 
I anticipate the need to run the Glowroot collector outside of our DMZ.  I also anticipate getting this question from our IT team.  According to the documentation grpc communicates over HTTP/2 so is the grpc protocol itself secure?   There can potentially be sensitive information in the request parameters and possibly other data I haven't thought of.
Thanks again,
David