I've used the Helix as an interface, but only in the context of a
Pro Review on Harmony Central to make sure it worked (my usual interface is the TASCAM US-20x20). Line 6's drivers have improved considerably since the days of the original UX-series interfaces. Helix can do eight ins and eight outs.
FWIW the Helix editor is outstanding, particular with touch screens. Don't forget to grab the latest Helix updates, as detailed in the above review. The new Snapshots feature is very welcome.
At NAMM 2017, Line 6 also announced that a software version of the Helix will be available in late spring/early summer.