re drop bags
I think what happened last year is that people used the multiple drop bags to store multiple sets of clothes/shoes over the course.
Then the high number of drop outs created a logistical nightmare for James and his team to try and get kit back to people over the following weeks.
You also run the risk of people not properly sealing them up after they have been used and so things fall out/get misplaced
I can see therefore why the intention is to just bin them, afterall, James is not meant to be providing a mobile wardrobe service.
A reasonable rucksac will carry all the extra kit you need, afterall, you cannot predict when the weather will turn into Armageddon, as it surely will.
As to an extra pair of shoes - if you are that worried carry an extra pair in a bigger rucksack, but to be honest you should have done sufficient long miles in the pair you start with to know whether they will be an issue
Sorry if that seems harsh