When George Miller had enough seniority he took the Leadville passenger train job out of Como so he avoided the tunnel. He had a reputation of saying exactly what was on his mind so I imagine he would have a comment about going up in there.
In Sam Speas book ``Goin' Railroading'' the author writes about a trip his dad took through the tunnel with a passenger extra. He said the trip took about 10 minutes. That averages to about 2 miles per hour so maybe it was a little faster.
The hoghead had to work steam through have the tunnel then shut the throttle off the other half. It was hard to breath in there and hard to see. He better not miss seeing that lantern at the apex.
It was Speas the younger who wrote that many of the old timers preferred a 16-hour trip over Boreas to going trough the tunnel. Perhaps they just hated Boreas less.