Well, I think u answered your question in the question itself. All the methods u mentioned have pros and cons and can be used, depends on the situation
Personally I like exchange partition approach, but it depends on the concrete situation
PAVBs method is simple, and reliable, that's what I like about it
IXION on the other hand puts that in dependency on the regulations, so all these factors should influence your solution.
Just to add, u may look at the
DBMS_STREAMS_TABLESPACE_ADM package in 10g Rel 2.