PS3 question: Full Back Up vs Data Transfer

Hello all, my question is simple: which method should i use, the full back up or data transfer?

Here is what i have; i have 2 PS3s:

- PS3-1 with 500GB

- PS3-2 with 250GB

- External HDD with 160GB

And this is what i want to have:

- PS3-2 to have 500GB HDD with all my data from the current PS3-1

I have Game ShareD games, game shared dlc's, and most likely locked saves.

My main concern is the GSD games and GSD dlc. Correct me if im wrong here, but everything else can be re-downloaded . And i will be uploading all the game saves to the cloud server, so don't have to worry about locks.

I have 2 options: (assume there will be 140GB of data)

- Data Transfer from PS3-1(500GB) to PS3-2(250GB)

- Remove 500GB, and insert 160GB into PS3-1

- DTransfer from PS3-2(250GB) to PS3-1(160GB)

- Remove 250GB, and insert 500GB into PS3-2

- DTransfer from PS3-1(160Gb) to PS3-2(500GB)

-OR-

- Full Back Up PS3-1 (500GB) to External (160GB)

- Remove 500GB and insert it into PS3-2

- Restore from External (160GB) to PS3-2(500GB)

I know the Data transfer method will be extremely time consuming. but it doesnt matter if its much safer than the Full back up method.

So the question is, which method should i use? Will they give me same results or one will give me better?

Thanks in advance to anyone willing to help.

PS: Excuse the formatting, wish I knew how to change it.