I think with this sort of thing, you have to consider the likelyhood of breakage.<br><br>If the nature of the application/configuration is relatively straightforward, and/or compatibility between the two versions is very strong, then I think the best thing to do is an automated migration.<br>
<br>If on the other hand, breakage is very likely, then probably "halt and prompt" is best.<br><br>An intermediate possibility, might be if the app has very good configuration file verification.<br><br>Then you could do the automigration, VERIFY it, and then halt noisily if it fails verification.<br>
<br>A post thought: in this case, I think you should always only copy; never remove. Worse case, 'mv' old config to config.migrated or something.<br><br><br><br>