I'd drop the ammo runt form the Mek, he doesn't have a gun worth rerolling to hit, and even though it's only 3 points we can hopefully add more to that later.
Your commando and deff dread are spot on. Snikky and a 4 dccw dread will strike fear into your opponent. I like your boyz squads, they are no frills and plenty of bodies. The stormboyz are a tough one though. You can use them as an alpha strike squad to soak fire early so your boyz can get closer, but they are really pricey for that purpose. Also, with only a t-shirt save, they really need cover to be functionable and as you have a large squad that will prove difficult. You could deepstrike them from reserves, but they can't assault unless you have Boss Zags as an upgrade. I would drop a few stormboyz and use the points to make that nob Boss Zags. Then deepstrike and take out enemy armor.
Your def koptas, I would put one per slot on your FA. That way they can act independantly. But your kans I would put in a squadron as one Heavy slot. That way they get some of the free bonuses of the squadron rules.
Other than that, the list is much better than my first list so great job!