When Line 6 increased the oversampling rate, a lot of people claimed the matter was resolved; others claimed it was "improved". It's worth noting that many others never thought it was a problem in the first place: they either didn't hear the artifacts at all, or they thought the artifacts were equivalent to what you'd hear on the actual amps. I was very staunchly in the "this sounds wrong" camp, and I personally didn't think the oversampling had any impact (though it did make the Helix sound better in other ways.)
Luckily, I've found a workaround that removes these "squirrelly bits" altogether:
-Be sure the Helix volume knob is set to max.
-Use a pre-amp EQ to apply a slight boost with low Q at approx. 1KHz.
-Turn BiasX all the way down, and bring Bias up slightly (amount varies with different amps.)
-Bring the Master volume down to 0.1, Presence to 1.
-Add a steep notch filter post-amp at approx. 2KHz.
-Add 3 LA2A compressors in series at the end of the chain, set to Stun. (This is the "glue".)
-Unplug all of the cables from the back of the Helix.
-Plug in your Quad Cortex.
Seriously, though - I've come to accept that I might be wrong about all of this. 10 zillion people can't be wrong, and I've only owned a few of these amps IRL anyway.