Of particular attention to diags monkeys
: I switched to a custom dropbear build in the Rescue Pack, w/ the same passwordless patches as in USBNet. It should also be using the same hostkeys as USBNet, and, provided the userstore isn't broken, handle your USBNet shared-keys setup. (But it is not the exact same build as USBNet, and as such doesn't absolutely require the userstore to be up to function).
(Also: ECDSA! Yaaaay.)