I have only ever used DC control. For a new layout I am being told that the cost of chipping 200 locos, that I have to run 5 different eras on a model (say 50/50 steam /diesel and of those 50/50 are with/without sockets) is less than the cost of a control panel with mimic track diagrams for a 12ft x8ft 3 track round and round layout with 60+ points, 30 isolated sections, and 15 signals.
Are you comparing like-for-like here? If you go full-DCC, then you will need to chip the 60+ points and signals too. If you don't chip the points and signals, then you will still need a conventional control panel for the points and signals.
When you say "the cost of a control panel with mimic track diagrams" are you paying someone to build and wire a control panel for you? If you build it yourself, it surely isn't going to cost very much. The simplest control panel is just a piece of ply or aly with rows of holes drilled in it, and toggle switches mounted in the holes. For 60+ points, 30 isolating sections and 15 signals you would need a panel with say 100 switches (you can often operate two point-ends from the same switch, e.g. if they are a crossover). So at say £2 a switch, a DIY panel will cost in the order of £200. You won't get anything like 200 decoders for that price - especially not sound ones! For most modellers, who build their own control panel, DCC is considerably more expensive than DC.
The big selling point of DCC for me is for the sound. The buzzing noise given off by the electric motor, particularly in a steam-outline model, just seems so unrealistic and annoying after you have experienced a sound-equipped loco.
Whilst the sound does depend on the quality of the speaker, it is also heavily dependent on the correct mounting of the speaker, in an accoustic chamber. Just plonking a loudspeaker any-old-where in a loco is likely to produce rubbish results.
DCC offers far-superior slow-speed running, as the loco is still receiving full power. However, in my experience, with DCC you do still need to keep your tracks clean, just as much (if not more so) than with DC. If the loco loses power, it will still stop dead! More irritatingly, a minor blip that may go almost unnoticed with DC (because the inertia of the loco keeps it going sufficiently to re-establish contact), with DCC can cause the chip to "reset", so it starts the loco from a stand again.
Personally, I don't like the way points and signals are controlled with DCC, especially if you have a lot of points and signals. Having to remember the code for each point and signal (or route, if you go that way) is just over-complicated, and I really don't want to go to computer control. I find it a lot simpler to just throw a switch, with a separate switch for each function, so like whhistler, I will be sticking with the traditional method for point and signal control.
I had thought that my DCC controller would control a non-chipped loco by using code 0, but apparently not. So I am keeping my old DC controller until I have chipped all my locos, with a switch on the panel to switch between the two controllers. I have a fairly simple layout, where only one train runs at a time, and the locos not in use will be isolated in sidings by the points, so I won't need any isolating sections.
It sounds like your layout is going to be a lot more complicated. Unless you have really deep pockets, it is going to take you quite awhile to chip all your 200 locos. In which case, you might want to think about how you are going to operate until they are all chipped. My suggestion would be to start with one of your 3 tracks as DCC, or switchable between DC and DCC, then as you get more locos chipped, to convert the second track to DCC, and so on.
As an electrical engineer, I have a concern about feeding such a complicated layout all from one DCC supply: any short-circuit, anywhere on the layout, could bring the whole caboodle to a grinding halt. And with everything connected in parallel, it could take quite awhile to trace the short-circuit. Perhaps someone with practical experience of DCC on a complex, multi-track layout might like to chip-in here?
