I noticed -- while I happened to be tailing my server.log file -- that some changes in the admin console in fact do (sort of) silently bounce just the domain. Unfortunately, the admin console doesn't do the best job of telling you when something "took effect" or whether you need to bounce the whole thing. But the server.log does show the "silent" restarts and they take far less time.
[Message sent by forum member 'russpet' (russpet)]
http://forums.java.net/jive/thread.jspa?messageID=323161