I've been using GTMetrix for a while now but have noticed that the results are very inconsistent - and sometimes just wrong. Gidnetwork will show compression working perfectly and GTM continues to state it's not enabled. GTM is showing "avoid bad requests" with the links it lists as being from a 3 week old version of the site.
It's like chasing smoke trying to determine which "tests" are showing accurate information when all testing sites give different results.
Does everyone out there just use all the well known tools and continue to work the site until ALL the tests show clean?