Well, this may be reason enough for me to dust off the old E3 Flasher… Looks like E3 are working on some great new stuff. Including ability to dual boot 4.21 and CFW. Sounds like the best of both worlds to me =)

012-07-25
1: E3 Flasher downgrade and dual boot 4.21 OFW successfully . We also successfully dual boot DEX3.55-CEX3.55 . We are studying other dual boot way like DEX4.2-CEX4.21, DEX4.2-CEX3.55 which can help E3 flasher user enjoy more function .

2: We are developing one key switch function for E3 flasher user. User convert DEX to CEX and CEX to DEX very easy ,just like our one key downgrade way.
We will release it free for E3 flasher user when complete.

3: We will release a great news for all PS3 user in next few days, and also with lots of free new game EBOOT .

~ E3-Tech

This is kinda cool. Looks like recently a couple of developers who go by OverX and HwapX have developed a nifty little tool called “Venix Downgrade” to assist in downgrading your PlayStation 3 from firmware 4.11 to 3.55.

Now, don’t think you are going to run out and do this with a little determination and a flash drive. Unfortunatley you will still need a NAND/NOR flasher of some sorts. This is compatible with; Progskeet, E3 Flasher, and Teensy 2.0++.

UPDATE: This has been proven to cause bricks… so I do not recommend using it at all!!

Download Venix Downgrade Tool – HERE

Features:

• Compatible with Progskeet, E3 Flasher, Teensy 2.0++ other.
• Compatible with NOR and NAND.
• Script to check malformed headers, File names, Region names.
• Check headers offsets NOR.
• Compares bits between two NAND or NOR.
• GUI interface.
• Patch to downgrade simplified.
• Automated Method
• Requires Microsoft .NET Framework 4

SOURCE