Yes Line 6 has done a bang up job over the years of making all there gear integrate well and there is something to be said for that but I think that perhaps some of the folks in this discussion are missing the point of the DT series. Maybe before you get super upset about the lack of integration presently available with your helix you should take a moment to appreciate the inherent differences in these two products..
I love all the modeling technology we have at our disposal these days, its come a long ways over the past 15 years and I presently own both the AXE FXII and the helix which I am just starting to learn the ins and outs of. I use the AXE FX all the time for gigging, band practice, and other working situations.. It is able to recreate an incredible number of amp models very well, offers massive DSP, deep editing, and routing flexibility that is unparalleled for the working musician but all of these modelers are designed to be run through either an FRFR get up or a true stereo power amp and cab. Ive tried running my AXE FX and helix through a number of heads and combo amps using either 4 cord method, in the fx loop or straight into the front end of the amp but I have always felt that doing so does nothing but diminish the power of the modeler. After much exploration I personally like the sound I get running my modeling gizmos through a good stereo tube power amp and a good stereo guitar cab. For me the ENGL e810/20 stereo pwr amp and a pair of THD cabs 2x12 is the beez neez and though this is entirely subjective I often times leave all pwr amp and cab simulations on..
The DT50 I own is in my mind a completely different animal and it appeals to the Tube amp purist the still lurks inside me. Of all the line 6 products I have owned the DT is IMHO by far and away the most accurate take line 6 has produced on any of the 4 voicing options you have access to without using any midi or HD connections. They sound true to the originals in a way that that just stomps all the other stuff L6 products I have owned including the helix. This is especially true of the classic Fender tones, class A, and classic Brit voicing. The DT seems to capture all the subtle nuances of the originals that none of my modeling products can quite nail. Im referring to things like the picking dynamics, the bloom or Sag of the power tubes, the inherent compression found in real tube amps etc.. I think this is because there is minimal modeling happening and a truly excellent Bogner designed pwr section that is far better than those found in any of there other collaborations.
Im just saying products are designed for specific purposes and you cant jam a square peg into a round hole.. Food for thought....