Gentlemen,
Although DCS does run most everything on my Legacy engines, I run both DCS & Legacy. Legacy/TMCC also controls my FasTrack wireless low voltage Command Control switches, using track power, directly from my Cab2 or TMCC Cab1 remote controls. Unfortunately DCS can not due this without the use of an AIU and wiring.
IMO it's best to have and use both DCS & Legacy, especially if you own FasTrack.
PCRR/Dave