Abby has a higher offensive ceiling than Helm IMO. Also, Helm will likely be better with Eaves and Mursak than Abby.
Helm's 32 points and 12 goals is far better than Abby's 7 goals and 19 points. Helm's production has increased steadily over the past seasons whereas Abby's has stalled.
Last year I would have agreed with you about the upside, but Abdelkader hasn't shown any of the offensive abilities he displayed in GR, where Helm is finally starting to bury his scoring chances (he also creates far more opportunities than Abby.)
I just think Helm has earned third line minutes far more than Abby has. (Im a homer for Helmer, though!)
I'll take a stab at some lines.
Maybe switch Hudler and Cleary if one or both need a jumpstart.