I am a founder of ScaleChain, which builds a private blockchain using Open Assets Protocol.
I found that Open Assets Protocol works, but it is too slow when mapping assets to coins as it requires back-tracking transaction inputs over and over.
I am thinking about proposing an improved version of OAP without the back-tracking with companies like MultiChain, which uses OAP.
How about working on the improvement together? My rough idea is to include an array of hashes of asset definition files for each output in the transaction into the asset definition file pointed by the asset definition pointer in the marker output.