I'm finding that newer version of software has slightly different responses. There appears to be two ways to handle this:
The question is which option above is the better option from a performance and maintenance perspective.
You are asking exactly the right question. Both of these options are reasonable under different circumstances and you can, of course, decide which one suits you better.
In general, we believe that your reference to "slightly different responses" is the key. If these two response formats are very nearly identical, then you are probably better off updating your existing map to handle both. But as they start to diverge more, you are better to create a new map to handle the new variant. In this latter case, you should be very careful about naming everything so that the new map is "backward compatible" with the older map -- so that the same queries work for both -- at least to the extent that they can be.
You mentioned "priority" and, yes, this will decide the order in which they are attempted. Note, however, that the logic will keep trying applicable maps until it finds one that maps without errors. So in most cases, you won't even need to worry about priorities -- as it should eventually find the right now. Having said that, there are exceptions. For example, if your new response has additional information compared with the older one, then it is possible that your old map will also work against a newer response, where you would prefer it to find the more complete information if possible. So you are absolutely correct that setting the priority on the map representing the more complete response is generally the right strategy.
