I've been using the PS2 SwapMagic 2.0 for quite some time on my version 4 PS2. It has worked fairly well as the only problems I've encountered is that Dodonpachi DaiOuJou's Death Label and Gallery mode crashes the PS2 into a black screen; same deal with trying to play the original Shienryu from "the Simple 2000 vol 37 Double Shienryu." Not a big problem since I'm having enough trouble staying alive for long in DOJ that I wouldn't dare try the death label and that I have two versions of the original Shienryu on the PS1.
But then I just got Psyvariar 2 Ultimate Final in the mail the other day and it wouldn't load past the "SoftDec/AD-X" logo screen. The screen would turn black afterwards. So I can't play Psyvariar 2 at all. Would getting the SwapMagic 3.3 make a difference?