Downgrade Help

I'm on CFW Rogero 4.30 and I'd like to downgrade and install a different CFW - which is Rebug REX 4.21 (or REX 4.30) - mainly because I want the DEX features.

So, all I need to do is:

Enable QA / Dehash -> use '999' downgrader -> Enable QA / Dehash -> Install CFW 3.55 (kmeaw?) -> Enable QA / Dehash again -> Install Rebug 4.21 REX (or REX 4.30) ?

Is that right? I just want to make sure because I don't want to make a mistake and get bricked. Thanks in advance!