About PUT and DELETE server support, we're using Apache2. Do you know if that's on the bad list?

Assuming I fashion a system using REST/JSON/AJAX, how big of a problem is it if consumers of the API say they would prefer XML? There are at least two solutions:

1) Give them XML, even though the core of the system uses JSON - how easy is this in a R/J/A solution, can it be just like adding another view in an MVC application?

2) Convince them that JSON is just fine - depends on how good the Java support for dealing with JSON is, and on whether the manager is thick-skulled. If Java support for JSON is not so great, then I have a political problem that may override the technology decision. According to the JSON web site, most languages have great support for JSON, but is this just JSON marketing, or is it true? Personally, I'm already sold on JSON, but I'm wondering what you (anybody) have heard about the difficulty of selling the Java people on it.