Despite various members went from DEX to CEX, there are still folks experiencing brick even though they have followed a working guide. It may be working for you but strangely it might not work for others.
Even though, NOR PS3 Slims should not have problem going DEX <--> CEX,
but I strongly suggest that you have a USB Dongle with you first before you attempt any DEX <-> CEX switching.
You could follow this if you experience a brick.
Code:
http://www.ps3crunch.net/forum/threads/4111-C2D-EXE-v2-(PS3-Flash-Patcher)-Now-Allows-Users-to-Modify-Region-TargetID-Settings?p=46086#post46086