Hi there, I would actually mix both solutions for best results. We need the chain to inevitably protect blockchain users from attacks and at the same time provide good value for distributed delegated proof.
So, my suggestion would be to use an off-chain solution as a service, but control the distributed use of it via blockchain solution. Something like the blockchain storage solutions like Storj for example. But in this case, we have the advantage of the bitShares based blockchain features.
Thank you for your input! I think Steem has better structure for storing messages rather than Storj but like I mentioned in post, there are pros and cons.