The new speedtest (speed.cloudflare.com) seems to give me very accurate results so far.
As stated in the FAQ, the service is meant to work as an alternative to existing speedtests, like speedtest.net.
However, a crucial feature which is missing is the server selection. Occassionally the auto selection picks a server in a different country, than my IP, which I would like to be able to correct by switching the test server.
Thanks for the tool! It works well so far and the Cloudflare infrastructure is a major plus point for testing.