I know i am a little late to this discussion but wanted to make a few adds:
1) There are two types of industrial rail trolleys. If it is the earlier version produced by the original "Industrial Rail" as opposed to "Atlas O Industry Rail", avoid them unless you are planning on transplanting the body onto an Atlas O chassis. They catch fire.
2) All 3-rail trolleys sit up high compared to scale models because of the large size of the wheels.
3) Atlas O models are very durable and reliable and plenty are available in the second hand market if there is a need to cannibalize for parts. They are small for their prototype.
4) I run an elevated loop and the smaller size of the Atlas O trolley gives a nice forced-perspective on a smaller layout, IMHO. Also the scale-sized 3-rail models tower over road vehicles if you run alongside streets unless the track is embedded in the roadway.
5) Bowser trolleys are reliable but not very detailed, often lacking windows on the ends. Also, I have seen the gears fail. I have never seen similar failures on MTH Brill models which are are by far, the most rugged.
6) Westernhobbycraft models are the most prototypical to their type. The motors are not as durable as MTH. They have alot of fine detail that can be broken.
7) Current Lionel Birney trolleys are a little large for their prototype but run nicely. Early versions of these would burn through traction tires.
Just a little personal experience.
