You're absolutely right.
I sortof lumped them together as readers,but fs-driver supports read/write.

Another type of explorer is Virtual Volumes by the same author as in #3.in my previous post.
http://www.chrysocome.net/virtualvolumes

One more advanced is CrossMeta from
http://www.crossmeta.com/crossmeta.html
However this is much more than I need,but very useful to anyone
interested in this setup.(Core and add-in)