Thank you for the coverage of this fun but truly pointless debate.  I have long championed the Hiawathas as World's Fastest, most recently here, upon my learning about your site.

On one of the other comment threads somebody asked about two articles in the 2002 Classic Trains.  Both are by veteran railroaders Ed King and Jim Scribbins.  One is a rather lurid story about Hiawatha 102 stripping herself passing Morton Grove station with a North Woods Hiawatha making about 90 mph, when the engineer's side crosshead seized account failure of a lubricator.  First the main rod snaps.  It tears up some of the cladding on the locomotive, although it neither comes up through the footplate to injure the crew nor digs in in such a way as to derail the train.  The other is some speculation about how fast a Hiawatha can go, noting that the Milwaukee Road never ran a speed test with the intention of setting a record (I'm imagining letting one loose at Tomah with 30 miles of sand-country running until it gets near to the Wisconsin Dells) and mentioning the running test with the recorder tape maxing at 125.

Stephen Karlson ATTITUDE is a nine letter word. BOATSPEED.