A big part of the design of Super Search is that it requires interaction to complete a search that would take too long (because it was vaguely specified and/or because the DB server is busy). This encourages people (who are naturally at least a little impatient) to either refine their query or retry at a different time (or use something other than Super Search).

An XML interface would either remove this `interactivity or likely automate it which removes the value of it.

So an XML interface to Super Search sounds like something that would be a source of problematic load. But that is just a first reaction (I haven't thought about it much and I have to run ATM). I'll contemplate further on the subject.