survey of DocBook 5.0 validation tools

I'm doing an informal survey for the DocBook Technical Committee regarding 
schema usage for DocBook 5.0. We would like to know among DocBook 5.0 users:

1.  Which schema type are you using (RelaxNG, DTD, XML Schema) and why.

2.  What editing tools are you using, and why.

3.  What validation tools you are using, and why.

You can reply to the list or to me directly if you like.
Thanks.

Bob Stayton
Sagehill Enterprises