I've done the secondary cat delete and am happy with the result.
I would say it's got 5-7% more volume, and sounds slightly more aggressive. No Cel issues or drone at all with the oem rear box.
I have tried different setups before which sound great for a Month, but then they would get on my nerves.
The secondary cat delete gives it a subtle improvement and is worth doing. The cats can easily be smashed out from their housings leaving everything looking standard once welded up again.