Heres something a bit interesting.
The chef from the new forthcoming "Authentic Balti Curry Book" says on their website he uses and recommends Cinnamon Quills and not Cassia Bark in his restaurant style curries.
It is interesting most of us on this site use Cassia Bark. I have e-mailed them with the question "where do they get their stock of Cinnamon Quills from" as I have never seen true Cinnamon Quills in any asian shop I have been in to.
Ray