Both my Variax 500s work just fine with the Helix. Model changes in Helix presets work great, the VDI cable works just fine, etc.. The one thing that doesn't work, and it doesn't seem like it would have been so terribly hard for Line 6 to have supported it, is using the Helix as an interface between an older Variax and the original Workbench software running on your computer. So, if you need to use the older Workbench software, you can use a POD HD500 (or 500X) or Firehawk etc., or the original interface that came with Workbench. Save your changes/tunings to the custom preset slots and then move back to your Helix. So your older Variax should work fine with the Helix, but not for editing in Workbench. If you are like me, this isn't a big deal.