I'm curious about how Mongo will react to a situation I'd like to perform as part of a rolling upgrade, and the documentation is somewhat unclear.

I'll be upgrading my replica set one at a time, which means each node will take several hours to catch up. I'd like to end up with my new members taking the place in DNS of the old members with minimal disruption to the set. My plan is, for each one:

1) Launch a new instance under a new hostname
2) Wait until it catches up
[Step down if primary]
3) Stop the original instance
4) Update DNS so that the new instance takes the original's place
5) Let Mongo figure out that it's properly up to date for a seamless transition
[Go on to the next one if needed]

First of all, is that a viable strategy? The original instructions we got from 10gen specified that we should shut down each server and relaunch it as the new version.

Second, would there be an issue launching all three replacements and letting them get into a replicated state so that my actual "upgrade" time is just the time for each member to figure out that it's healthy once switching each hostname in turn?

Any tips I should know about?