What evidence do you have that there were ever more than the 200,000 bitcoins found in the "old-format wallet"? Earlier in the year, these bitcoins were worth in excess of $100 million. That's a very large cash hoard for a 3 year old company run by a 28 year old. It stretches credulity to believe Mt. Gox actually controlled $500 million in bitcoins that has been claimed. Nobody has demonstrated that those coins totalling to the larger sum ever even existed. More than likely, it is just another wild claim.
The ~800'000 BTC figure is the sum of all BTC balances in client accounts.
I know about the leaked database, but it was incomplete and missing a lot of data. What backs up this 800,000 number? No depositors have been allowed to look at these books to be sure that this number is even in the ball park. The $500 million or 800,000 BTC sounds way out of line for an exchange like Mt. Gox. 200,000 BTC sounds a lot more realistic.
If the exchange had been operating as it should, that number should be the sum of all BTC deposits by clients, minus all BTC withdrawals by clients and the fees withdrawn by Mark & co. So those bitcoins would have to be "real".
If those bitcoins did not really exist, there must be inconsistencies in the records, like bitcoins being credited to client accounts without corresponding BTC deposits, or BTC withdrawals without debiting the client account. Mark claimed that the latter was the case: the "malelability bug" tricked his scripts into doing precisely that. But people who understand the "bug" say that it could not have leaked more than a few hundred BTC. And Mark has been silent after that first "explanation".
Given their obvious exaggerations about losses from transaction malleability, all of the company's statements should be regarded as highly suspect, especially the one that it once held 850K bitcoins.
I don't see what the Sunlot takeover has to do with an out-or-court settlement. When depositors and creditors work out a settlement, it could return all of the depositors' bitcoins from the 200,000 BTC stash, and there would be no need to convert to Japanese Yen. This is something completely different than Sunlot. While representing a compromise of interests, it would be a good one--essentially a win-win for everyone. Proceeding with the liquidation seems more like "delay-delay" and "lose-lose". Out-of-court settlements when they can be obtained are generally far superior in outcome to proceeding on with a bankruptcy liquidation. It will require creditors and depositors to come to some kind of agreement based upon mutual interests.
The first thing that a self-help group should do is to hire a lawer who knows Japanese bankruptcy law. Without expert advice, the group will be just a version of this thread: clients will waste time discussing what they would like to happen (like "return the BTC as BTC") without regard for whether it is legally possible or not.
Agreed, all in due time.