After a recent support email from a customer, I have finally gotten around to testing Stems with my mapping for the Behringer CMD DC-1. When Traktor Pro 2.9.0 the mapping installs correctly and functions as it did in previous versions of Traktor. Because of the generic way I implemented Remix Mode accross all decks, if you switch to Remix Mode and select a Stem Deck (which seem to currently just look like a Track Deck with enhanced background functionality) then the Remix Slot Filter and Volume controls work, and pressing SHIFT accesses the FX assignment allowing you to apply FX to just one part of the stem.
When I tested stems with my Kontrol F1, the F1 acts much the same, but now allows you to chose a Stem Deck when previously you could only select Remix Decks. The new functionality of the F1 is a level meter effect in each column of buttons to indicate what is going on in each slot. I haven’t dug deep enough yet to know if this is possible with the CMD-DC1 and Traktor 2.9.0 – new outputs don’t seem to be available to assign and based on history, NI usually wait a few releases before unlocking such functionality to external controllers.
Having finally taken a look at Stems, they aren’t quite what I expected, but I have come accross some press that waveforms are limited to controllers like the D2 and S8 for now – which is clearly a major drawback of the F1 or 3rd party controllers like the CMD-DC1.