Since coil has started... no competition and I have YET to see allagan caster body. I bet there is a extra secret rate that is based on guardians/party comp.

I.E. if you stack a lot of X that may not be what you get. Though I will say I've seen less healer drops overall still in my months doing coil. So it could very well be broken and we'd never know because we don't know rates and they won't investigate unless a bug report is submitted -.-;