Best way to maintain a set of test databases.

I need to setup and maintain a set of test databases and I am wondering what the best way to do it would be.

Given the following scenarios

1       Create database
2       Install application schema
3       Load test data set 1
4       Back it up (A)
5       Load test data set 2
6       Back it up (B)
7       Install application upgrade
8       Load test data set 3
9       Back it up (C)

etc.

At the start of a test cycle one of the backups at A,B or C needs to be loaded into the database.

The possibilities I am aware of are

exp/imp - may be a bit slow with the data volumes involved rman backup/restore of the relevant tablespace. Looking through the rman manual, tablespace point-in-time recovery looks very complicated. Is there a simpler way?
transportable tablespaces - can I remove and reattach the same tablespace at different 'ages'?

Any suggestions are welcome.

Oracle 9.2

TIA

-- 
Jim Smith
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