I know that this thread may have moved on, but I have an idea regarding the recent slew of sole swaps and shrinkage. Have you guys tried leaving non-spring-loaded plastic shoe trees in the shoe while boiling / heating them up? They hold the shape of the toe box and generally hold the shape of the shoe during the heating process.
Pics of shoe and shoe tree:
Inside the shoe:
This is after washing this shoe, you can see that the shoe trees hold the shape of the toe box quite well. For those that are brazen enough to attempt swapping soles, and/or for those that would like to avoid certain washing machine mishaps (they stay in the shoe during the washing process) or the Ikea shoe tree phenomena, these might help.