SawTroll
Information Collector
So just running the stopwatch on my phone I'm seeing a best of 6.46 for the 550, 6.08 on the 562, and 4.65 on the 2186.
Of course the two larger saws are slinging 20 percent more chain so I'd expect times to improve commensurately if this was a true scientific test.
Eliminating chain differences is quite simple, but regardless what you do, a cutting comparison just tells what happened there and then - not what will happen in other wood and/or with other cutting attachments.
Have fun, and don't take the results more serious than they deserve!