PRO: The biggest single reason, IMHO, for trolley modeling is space: an 0 scale trolley layout could be built in no more space than a classification yard would take up on a conventional HO layout.
[The narrow guagers tend to use the same argument.] The prototypes used curves all the way down to 32' radius, which translates as 8" in O scale or 4 1/2" in HO; my personal recommendations, based on
my experience, would be a minimum radius of 9" in HO and around 15" in O for anything larger than a single truck streetcar. Additionally, since most traction properties were small, typically less
than 50 miles of track while a single division of a major railroad might have a couple hundred miles. It should be obvious that your 50 or 100 feet of modeled trackage can more faithfully reproduce
the prototype.
Next, the plethora of prototypes, large and small, makes it much easier to confound the rivet-counters and nitpickers. Paint schemes almost covered the entire rainbow of colors and equipment types
came in more varieties than Heinz. The richer companies had 'standard' designs customized to their own specs, albeit from any one of literally dozens of makers, each with their own 'standard'. The
poorer companies [i.e., most of them] made do with what they could find on the second-hand market or what their own shops could build. Some of the imagination, shade-tree engineering and outright
scrounging that went on to keep something, anything, running staggers the senses.
Thirdly, if you are just a bit of a nitpicker at heart, trolley modeling is inherently closer to prototype as your models are powered just like the real thing, electrically, and preferably from live
overhead, while the majority actually runs their so-called diesels and steam engines with ELECTRIC motors.
CON: The selection of RTR or even kit equipment is much more limited than for our more traditional brother modelers, especially in the lower price ranges. Bachmann has a Brill Suburban, a PCC, and a
cable car RTR while Bowser makes several fairly easy to build kits including the Brill and the PCC as well as a couple others. LaBelle Woodworking makes a line of 'craftsman' type kits in both O and
HO scales that require more patience and attention to detail, but produce some very good looking and different models. MTS Models is an importer of brass units at the upper end of the price range
with good detail and reportedly decent operating characteristics.
If you are interested in an "electric railroad" there are several locos available with the most common being several manufacturer's version of the Pennsy's GG-1; although at this point you lose the
space advantages of trolley modeling. For an electric shortline, MDC's old-timer diesel is relatively easy to modify into a believable box-cab, and Cary Locomotive Works [Bowser] makes a conversion
kit to fit the Athearn Hustler [and a few other 2 axle diesels] that is also easy to modify for a trolley switcher.
The biggest bugbear about trolley modeling is the overhead, which looks terribly, complicated and impresses the viewer no end, but in reality, it just requires patience and practice. It is basically
just a few simple steps that you repeat and repeat and repeat If you can do a clean solder job on a few components on a PC board, you can do overhead. More on that in a separate section.
Jack "The trolley nut" Priller