Last time I post about it here - it's up to you guys, but instead of trying to get ''perfect'' solution, why don't you just push for an actual realistic solution ?  Steps are simple to send back coins using V1 DB.  Sure it is not perfect, but its 90%+ accurate since few trades had been made on V2.  We are doing it now for Fluttercoin, and it's an easy process:

- We sent an email to each Mintpal customers with a V1 FLT balance, asking for a withdraw address.
- We send coins back.
- Repeat.

For us, there is a gap between wallet balance and users total balance, so we send balance minus 8.95%.  As I said, its not perfect, but it is 100% better then most of other coins in crypto, so we accept the little loss, and move on. 

Asking for password, waiting, round 1 - 2 etc is just a pain in the ass for whoever have to handle it, and may even get him legal problem later.

We sent back 20 000 000 FLT out of 58 000 000, I would say it's a good start.  We are now sending another email.  And as a community, we decided that if it was unclaimed coins, we would just let them sit forever.  We don't have any right to use it, or to delete it.  So if ever we face some legal question, we will have every single proof or transactions we did, + all the remaining coins. 

As I said, up to you, but it's so simple that way. 

Good luck u guys !