Two things:
1) Is Eternal Warrior (and using a Power Fist) that important to you? That shield is damned expensive compared to a Storm Shield. Dropping it and the Fist for the Burning Blade seems like a good idea to me, or trying to add more Missile Launchers to your Devastators (well, Missile Launch
er).
2) Especially since you are using the Commander to give the Devastators Tank Hunter, the Quad Gun would be better than the Icarus Lascannon. Both for anti-Flyer/Flying
MC as well as
AV 12 ground targets. 4 Twin-Linked
BS 5 shots gives you 3.89 Hits (so near perfect accuracy). That's 0.65 Glancing Hits and
0.65 Penetrating Hits against
AV 12. 1.30 Penetrating Hits against
AV 11. Compare to the Icarus Lascannon's 0.83 Hits with 0.14 Glancing Hits and
0.42 Penetrating Hits against
AV 12. 0.55 Penetrating Hits against
AV 11.
Maybe if you had
IG Orders to give the Icarus Lascannon Twin-Linked... I'll grant you that the
AP 2 will help when you actually Penetrate, but its just less reliable overall. Since you said "COMP" in the title I assumed you want competitive oriented advice, so reliability wins out.
Other than that... Well you better hope you go first. You have a lot of bodies, but volume of fire takes out
MEQ easy enough. Your Scout re-deployment (its not a move anymore; its kind of an important distinction) will help getting you close to the enemy, but you'll be outside Melta range no matter what on Turn 1 unless you actually move (and thus Snap Fire). There is nothing really scary present in the list other than the Riptide, and single Riptides are not that hard to handle.
You'll have some fun games, with high casualties but I wouldn't expect it to perform super-amazing.