Is there any advice about debugging DAS?

Byron's 2 cents on debugging DAS:

If you want to break early in the process – edit your domain.xml and set suspend=y in the debug-options
in the java-config element.

Now start the domain like so:
startserv -v --debug
or
asadmin start-domain -v --debug

Attach to DAS at port 9009 with NB.
When you don't specify --debug then DAS isn't debuggable.
If you want DAS always ready to attach, then set debug-enabled=true in java-config. Make sure suspend=n or you
will be very annoyed!