I know this is resurrecting an old thread, but this kind of answers the first question I was going to ask.
Everywhere I have read on the net has said species only, it was the same with my green spotted puffer, BUT, the all LFS I visited that said they could supply, did say they would be alright together if of a similar size. My GSP is only 2" and probably won't reach it's 5"-6" MAXIMUM adult size most stop somewhere in the region of 4" - 5", that said, I still won't be attempting to keep them together when my puffer reaches the marine stage of life.
I totally agree, that poor little cuttlefish should not have been in with a porcupine puffer that can reach over 1.5 feet in length.
If however there is an unfortunate incident, this will be my first port of call for continuing to research, and sourcing a captive bred sepia bandensis.
A huge thank you to all involved in creating and maintaining this fantastic resource, I fear if I had not found this place then another little cuttle would have suffered a similar fate.
I hope to be back again at some point in the future as these really are amazing little creatures