Sambavan,
Just a remark: incremental (cumulative...) mode of export was not introduced in 8i nor in 8.0, it was awailable way back, at least from version 6.0. So if it is awailable for mor than 10 years now, you can bet it will be awailable for at least another 10 years (until the release 17j, I suppose ;)).

edwtsang,
If you are on 8i, why don't you explore the "transportable tablespace" option - I think this feature was made exactly for the cases like yours. In essence, you group all the objects in your production database that you want to transfere occasionally to your dev database in one or more "self-contained" tablespace(s). When you wan't to transfer them, you simply put those tablespace(s) in read-onlymode, copy the files to the dev environment and "plug" them into your developement database.

Check the documentation enad technet for details.

HTH,