I don't think sending the majority of all SPR to escrows is a good idea.
I'm not comfortable with risking it. I find burning to be also a bad idea.
Why not just set a future block and use that date to determine all SPR balances (ignoring all transactions after the selected block height) and have people sign their addresses to prove ownership and claim?
This requires manual work but latecomers could claim as well because it's clear to prove past balances.
A full snapshot would probably be the best solution but what would happen to exchange addresses with lot of coins?
But with manual swap the devs would have to also hold a huge amount of coins waiting for swap which some might dislike.