Well, perhaps the day has come. When I started my layout about 2004, I designed the wiring to easily be upgraded from my old Keller OnBoard control system, to a DCC system. I've withheld actually doing that because I've already got (and paid for!) the Keller system, and (until now) it's done everything I needed.
However, that has changed. To date, I've actually only installed decoders (Keller called them throttles, but in this DCC-age I just call them decoders) in diesel locomotives, mostly Athearn's I've remotored w/ Sagami can motors. The Keller decoders work well w/ these motors, albeit with a very slight buzzing at low speeds (due to the pulse-modulation used by Keller to help start older / cheaper motors).
But now came time to install decoders into my Spectrum 2-8-0 Consolidation steam locomotive. The wiring was simple enough - removed the built-in circuit board, hard-wired the connections between tender and loco w/ super-flex wire (pulled from old computer mice, btw), and added the decoder in the tender. Then came testing - and a very loud buzz in the lower 1/3 of the speed range. That pulse-modulation doesn't work well w/ these much newer, and much smaller motors.
I tried everything I could think of - different versions of the Keller decoders, adding the Bachmann circuit board back in, etc, but nothing fixed it. I guess this is a limitation of these old decoders, and one of many reasons the system isn't used much today.
SO - where does that leave me? Time to upgrade to DCC, I suppose. I like the idea of more control, more features, current technology, all that stuff, but I'm not happy about the re-wiring needed to locos and control panels, nor the cost.
Any suggestions on which brand, folks? I'm probably leaning toward either DigiTrax or NCE, and it seems at a least a couple of radio cabs make the most sense.