Hi Bradley,
I'm using my Helix in a recording studio not a live situation. So my answers are only from my limited experience with the Helix/DT all of two weeks.
I do have the Line 6 Link connected to the DT but after all my research I don't really think it's doing ANYTHING the midi commands are controlling
all of the DT settings. Line 6 Link is there but I think it's doing ZERO. Maybe a tech can clarify.
I'm using the XLR out into my DAW from the Helix no mic on DT. My guess is you could go either way. From the Helix I'm getting great tone into my DAW you would use the XLR out to a PA with no problems and get the same result. You can control the XLR feed volume and make it different than what's being fed to the DT I haven't done this but I"ve read it's doable.
You can control the CAB, Mic, Mic distance and SO MUCH more from the Helix and dial in your exact tone. Why use the DT cab with a mic? That's just going to change the nice tone you dialed in.
I can do quick how to videos let me know if you need help on any of this.
Gary