Choosing a digital system

As my collection of rolling stock grew, I wanted to run more than 2 locos on my layout, so I started to delve into the world of digital control. It was quite confusing at first: Fleischmann had their own system (FMZ), but it was already obsolete at that time, so I looked into the alternatives, and finally I chose DCC, as it seemed to universally accepted, and not bound to one manufacturer, like the Märklin system, Selectrix or Fleischmann FMZ.
However, the things I needed were at least a digital controller and booster, and these things were quite costly: for instance, the Fleischmann Twin-Center cost about € 600-700 (£ 500-600), and then I had to add decoders for the locos and turnouts... I knew at some point I wanted to add some amount of computer control to the digital system, so I did not want to commit too much to one console based system. And anyway, the more money I spent on such a system, the less I could spend on the visual items: rolling stock, scenery, etc. So when I found that Roco bundled a basic DCC control set (MultiMouse) with most of its starter packages, and that you could buy such a control set separately from eBay for about € 80 (about £ 70), I decided that I would start with that and decide later on whether I would buy a more professional system.
The disadvantages of the Roco system were clear from the start:
no feedback connectivity: for this you needed to buy the 'Rocomotion' interface, which came with software, but you still could use only the Roco feedback modules.
No programming track/CV read possibility: it was possible to program loco decoders, but you had to use the same output, and it was a 'blind' method: you could program a value, but without reading them back it was difficult to set things like maximum speed, etc.
There was no connectivity to an outside system, for this you also needed the Rocomotion, which cost about € 200 (£ 175).
So I bought this system and was busy for a while converting my locos to DCC, electrifying my points, and learning all about the quirks of digital model railroading:
For one, I went looking for decoders to control my electrical points, and was flabbergasted at the prices: the cost could amount to about €10 per point (£ 7,5), and there was no clear advantage to using 'generic' decoders to simple ones. I found a german manufacturer who offered decoders for about € 5 (£ 4,50) per point, and I have been using them ever since.

 They are quite simply made (using only a PIC microprocessor and two driver ICs), but robust enough, and I even managed to repair some after a serious short-circuit, by replacing the darlington chips used (the two larger ICs in the picture):

This IC is used rather often, I have found, and the decoders that are built with it have a negative output (pins 11-18) relative to the common conductor (pin 10). The decoder could be powered by the DCC signal, using a simple diode switched in reverse to supply the voltage (which would have a duty cycle of 50% max, since DCC is basically a DC voltage with alternating polarity), or you could cut a wire and supply a separate feeder voltage. If you would use AC, it would also have a 50% duty cycle, so it was better to use DC and supply a negative voltage.
I could combine this decoder with the circuit for the LEDs described above, simply by tying the 3 poles of the switch to the outputs of the decoder.