Hey @shaunvdberg , the RTT logic to determine what server to connect to is used quite often for different use-cases. When you mentioned wanting to build an e2e latency monitoring tool it reminded me of this video by @Aaron https://www.youtube.com/watch?v=AZDP8DbyfmE where he talks about round trip time to choose the nearest broker to connect to. Tho it’s not that related to your original question, but its a cool demo 
Also, Aaron had his regular office hours and talked about this post as well you can check it out here https://www.youtube.com/watch?v=zKR6LKvWGHI