Two Questions about E3 Flasher

Okay so I'm thinking about buying the E3 Flasher Limited, because I don't really play online anymore and I want to be able to have homebrew on my PS3.

So I have 2 Questions.

1.) If I update my Console to 4.20 OFW, will the Downgrade from the E3 Flasher Still work?
I checked online at other forums, and people said yeah because it's a hardware mod so they can't patch it without changing the whole design of the console.

2.) My Slims serial is: CG174511234-CECH-2001A so would I be able to actually use the E3 Flasher or no?

Thanks
~No0b3rT

1. Yes, it'll still work, but those people are wrong. Sony can still patch hardware downgrades with software updates. Remember, many software updates come with pkgs that update more than just what's on the flash.

2. Yes, you can use E3.