EV Access from Exchange Online & migration

Hi,

In an O365 Exchange hybrid migration, once a mailbox is migrated from Exchange on-prem to Exchange Online is it still possible for a user to access their archived mail in EV?  Will stubs still work?  I've searched but can't find an answer.

For migrating EV to Exchange Online, I've seen TransVault and Archive Shuttle mentioned, has anyone got any migration feedback on these providers (or other providers)?

thanks