I think the reason the migration tool leaves the Windows providers as defaults is the facts that all Sql users get their passwords reset. So you can't log on to your migrated site. With the windows provider though, you can log on with a local windows administrator, just like you're used to from 4.6.
Alternately, the migration tool leaves the provider that was configured in the new empty CMS 5 site before the migration. If i remember correctly, this is also the windows membership provider, for the same reason as above.
You can change this setting any way you like.
Thanks for the background info.
I have used the migration tool to migrate an existing site to CMS5 R2, on checking the web.config I notice the site is using
rather than SqlServerMembershipProvider, I wonder whether this is a byproduct of the migration and is there any need to keep it rather than revert to SqlServerMembershipProvider as new CMS5 R2 would be?
Thanks a lot