* Is this a good idea?

i think so.
   
   * The default globaldebugdir is: /usr/lib/debug
     I think that this should be:   /usr/libdata/debug

i totally agree.
   
   * Would we ship the debug files as part of the set that they're relevant to?
     Or the comp set?
     Or separate debug sets?  (eww, more sets to deal with)

part of comp imo.
   
   * Any other comments?

please do this :-)