You've put Devs under Elites...why? They're Heavy Support.
Anyway, I beleive you should replace the meltas on he Assault Marines with flamers, I know from experience it can be effective, and meltas aren't of much use on a CC unit.
And yeah, could you give us a template for a battle plan (template because, obv, you'll have to adapt to different opponents), and we can give you further advice.
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