My guild just downed Magmaw HC last night as our 4th boss before maloriak V&T or conclave and found it quite easy, we used a very similar raid comp to you and probably have around the same average item level so i would say go for him next.
For ODS pray to RNG gods you get 0-1 Shadow Conductors (Our down attempt like 50-75 trys we got 0). Your shamans should have focus macro to interupt arcane anhilator. Tank get 1 Shaman Tank Shaman make it so your dps doesnt have to stay on him. Magmaw is just like normal in P1 with adds (skeles) and fire have 3 people in range rest in melee make sure you get a head phase the same time hes about to push into P3 in P3 EVERYONE spread and massive heals Tranq/Healing rain anything you can do BIG BIG BIG AoE heals and lots of heals on skele tank he should have all his CD's up if hes a pally he should bubble cancell aura macro and get them back helps save a bunch of damage if hes good and such. Have a DK pref or hunter kite all the little parasits