I agree 100% on the minting to new holders only. As unfair as it may sound, the idea here is for these to be unique new user acquisition drives, meaning existing treasure holders should not participate. The intention of the drive is to benefit the existing treasure community, so sharing more rewards to existing members is defeating to the strategy.
With the L1 treasure migration strategy, this is something we definitely are aware of, and we definitely do want all treasures on L2. We need to put thorough thought here (and we will).
With the first 2 acquisition drives we have been putting effort into, with some almost complete for launch, these would not lend themselves directly to the treasure migration strategy you have, although in writing this, I have thought of something I will propose to the team.
While it is not finalised, just a reminder that one of the concepts for Riverman was that he would be a ferrier across different metaverses, and it was an idea that rivermen holders could ferry treasures from L1 to L2 with rewards for their efforts. Please do not take this as a literal happening, just putting concept to the ideas that were originally floated and to reassure that getting treasures from L1 to L2 is certainly a priority.