A few more thoughts:
Some of the best “bang for your buck” with DCC comes on a small layout where you might desire to operate several locos in close proximity to each other.
DCC equipment and wiring for a small layout, without signaling, detection, CTC, multiple reverse sections, multiple power districts, etc, is both simple and relatively inexpensive.
It is in this application that the cost difference between DC and DCC is relatively small. Especially if we assume the small layout only has a small roster of locomotives…
And, if you do like onboard sound, a small layout with only one or two locos operating at the same time, is the best “showcase” for onboard sound.
As layout size AND/OR complexity increases, the cost, and wiring complexity can increase exponentially, with DCC or DC.
Large DCC layouts require power buss wiring, power districts with circuit breakers, additional boosters, possibly multiple auto reverse modules, etc.
And larger layouts generally have larger fleets of locos…
If I were to switch to DCC tomorrow, I would need to begin the installation of 145 decoders. Now some will say don’t convert all your locos, get rid of the older ones, you don’t really need that many locos.
BUT, who are they to define my modeling goals?
My new layout, right now in the planning stage, construction to begin soon, will stage about 35 trains, have a 240’ double track mainline, and have several industrial belt line switching areas separate from the mainline, as well as a 22’ long, 8 track, freight yard.
Average freight train length = 35 cars.
The typical freight train will require 3-4 powered diesel units or two medium sized steam locos to handle the 2% grades.
25 freight trains x 3 locos = 75 locos
10 passenger trains x 2 locos = 20 locos
10 self propelled passenger motor cars (RDC’s, doodle bugs)
Extra locos for operational