DCC decoders have some of those features almost 6 years before MFX (like 128 steps).

As far as I know internally both systems are very similar with a different protocol. In use they are almost identical. At the beginning of MFX the only advantage was the loc detection, but in DCC that feature is called "Railcom" and it have been in the market for about 3 years and right now is fully operational (due to compatibility and standardization process). Any new technology improvement in DCC has to be approved by a standardization NMRA board, so any new feature can take some time to be fully implemented for all DCC brands.

Both technologies have big growing potentials, for example they can add more and more functions to decoders with just a minor central update. Actually some updated DCC centrals can manage 29 functions.

AFAIK DCC can have 32767 functions per loco address.
An IB with software version 2.0 (vapourware for several years now :-( ) will support 9999 functions per address (even more with the new IB II).

The CS 1 with software 3.0.0 will support 20 functions per DCC address.

Advantages of mfx? From my point of view there are none (because automatic loco registration can't be turned off).
I had problems with locos that ran fine on MM protocol but failed to register with the CS. Since automatic loco detection can't be disabled, these locos would not run - nor could the be programmed with the CS 1.

Another disadvantage of mfx: you need a LokProgrammer or at least a CS 1 to adjust some of the (basic) settings like speed curves. intensity of head lights, function assignment.

Well - there really is an advantage: loco functions automatically receive an appropriate symbol - this can't be done with many DCC symbols or is left as an excercise to the reader ...
The loco name could be an advantage, too (but M* normally goof the loconames up so I change most of them (but at least the loco remembers the new name)).

I hope there are more differences between MFX and DCC, or Maerklin will become an ever shrinking island of incompatibility with the majority of the digital model railroading world. It has prospered as the main 3-rail manufacturer, but one could argue that one reason it is having difficulties is that many other companies are starting to compete with them to supply rolling stock for 3-rail AC. Given that most of that will be DCC, it seems that it is inevitable.--MM

There are also differences in speed between different DCC centrals architecture, for example Digitrax central based on loconet is way faster than lenz xpressnet network, nevertheless even in huge layouts, xpressnet network from lenz it is more than enough.

In the forward direction I can't see any major advantages or drawbacks with any of the protocols. I think mfx is slightly more DIY-friendly than DCC, but it is just marginal. I have implemented the low level parts of both in my home made control system, so I think I know what I am talking about.

For the return path, there are bigger differences. The DCC Railcom allows for much higher reverse bandwidth than mfx. On the other hand, the Railcom electrical principle is far less robust than the one used by mfx feedback. This is from a theoretical perspective. Implementation issues could make the robustness relation different in practice.

Forward DCC and forward MFX can coexist without problems. Implementing both in a control unit couldn't be much of a technical issue. The reason why it has taken so long is probably market related rather than technical.

For the backward channel there is an added cost if you need to support both. Since they use different electrical principles you need separate circuitry for each protocol. That is not the case in the forward direction.

mfx uses "four-digit" addressing (14 bit IIRC) - but mfx decoders used with MM protocol only support 8-bit addresses (1 through 255).
DCC decoders used with MM protocol sometimes only support addresses 1 through 127 ...

Ray: The issue isn't whether you can see it, but remember it. You might get to know all your machines with numerical neumonics, and the more digits your brain has, the better. However, as our eyes become less powerful, so do our brains.--MM