Well this is coming on a month since you posted this, but better late than never.
Over all I like your list, you could swap a little versatility for effectiveness and give the command squad all melta guns, and have two heavy flamers and three combi flamers and put them with Vulkan. Your dual H flamer landspeeders will either get ignored until they incinerate a unit or get shot off the table before they can do anything. You don't have a lot of dangerous vehicles on the table turn one, so you'll likely lose the landspeeders or some rhinos very quickly as enemy anti tank doesn't have many threats to choose from. I wouldn't expect your sternguard to last until turn two, they're suicide units and will be dealt with accordingly.
I'd like to know how this fairs though, I've definetley thought about very similar lists.