The SHS locos are already 'DCC Ready'. Out of the box the dummy plug is set for traditional 'S' AC operation. By rotating the plug 180deg it switches them to DC operation, like HO/N.
By removing the dummy plug, and installing an 8-pin motor or motor/sound decoder and speaker you get DCC operation, with or without sounds. Which is what I do, and why I don't particularly want to pay for DCS to be included when I won't be using it.
Actually, unless ordered for DC operation, non-sound AC SHS loco's had an electronic 3-position reverse board installed with the DCC shorting plug included in the box. I have a small collection of SHS reverser boards lying around here somewhere.
The first run SW1's were wired backwards and SHS sent a "reversed" shorting plug on request. I simply reversed the motor and lamp leads at the 8-pin plug on mine.
As far as MTH goes, it's only been a week. I don't think even they know how they're going to handle things yet.
Rusty
