I'm currently raiding with HB and a slightly modified version of PartyBot. (may make it to public release if all works as planned)
Currently have it properly getting out, and in, AoE mechanics. (Eg; moving out of the void zones during V&T, getting out of meteor rings during Halfus, etc. Will also get in the Arcanotron swirls (sorry, I forget what the name of it is :X))
The bigger issue is with targeting, and ensuring its doing what its supposed to. On certain fights, I've had to script behaviors to occur at certain times. (Eg; on Chimaeron, when the bot is knocked offline, I have it run to the designated stacking spot, and throw down any AOE heals it has)
To be honest; HB is more than capable of dealing with raids, however, the default logic doesn't quite cut it. (Also; we may need to start thinking about implementing support for the spell queue system in WoW, as queuing a spell, and waiting for GCD/stopcasting, can mean the difference between 8k DPS, and 13k DPS.)
Currently running Resto Druid, Resto Shaman, Shadow Priest, Prot War, Frost Mage, and Destro Lock. (Prot war being the main, rest being slaves, running scripted-ish behaviors)