Matt,
The vibration I was referring to in my post was not a vibrating stirrup but a vibrating mirror which would reduce the vision of the engineer who was trying to see signals passed by a trainman.
Because of the position of the engineer in the cab of an F unit he would, by necessity, have to use the mirror to see signals in order to be able to also reach the throttle and brake handles.
While you tiny trainmen will "do what they are damned well told", from practical experience, I would not be happy to work off an F unit if there was an alternative. Depending on the period modeled you could have a five man crew available (Engineer, Fireman, Head brakeman, Rear Brakeman, and Conductor) so switching on a local freight might not require a lot of riding.
In a more modern era, assuming your railroad has bought F3 A units because of a cheap price and aesthetic appearance rather than a more practical, operational reason then you might be working with a three man crew (Engineer, Conductor, and Brakeman) in which case a lot of riding on freight cars or engines would be required when switching out cars to get them in the proper order or to set out and pick up at an industry. Thus the danger aspect of working off an F unit comes into play (climbing up into the cab of the trailing unit to ride back to couple cars is far too time consuming and tiring to be a practical alternative to riding the stirrup).
Anyway, you are the executive-in-charge on your miniature railroad and your employees will do what they are told or go look for work at a railroad that uses road switchers for local drills. The loss of your employees is offset by your knowledge that your little train guys will most likely have to relocate to a distant state, lose their seniority, sell their little plastic (or laser cut company houses), take their, even tinier, children out of school in the middle of the school year, and say good bye to all their tiny friends... And all because you insist on using F3 A units to switch your industries.
With the reduction in labor costs the railroad's stockholders will be overjoyed and will, most likely, vote you a huge bonus...enough to buy more F3A units for your expanding roster.
Steve