Important to note: With lower firmwares, you need a PSP game and you won't be able to download it from the PSN because the firmware isn't up-to-date. You need an up-to-date PS3 to transfer the game to the Vita, and there seem to be some issues recently surrounding that.
3.52 and above are not exploitable for the native hack, Rejuvenate. It does not offer much at the consumer level at this point, but it does have more power than just PSPemu hacks. For example, you may get slightly better results with more demanding emulators, like N64. There are some other little customizations that are possible with Rejuvenate, but right now it is still unclear just how far native hacks are going to go on Vita. It's up to you if it's worth it... But if you don't have a PS3, you might as well forget it anyway.
It's my opinion that you're better off simply buying a 3.55 and Mimana lyar Chronicles to exploit it. Since it's the current firmware right now, you'll get access to the PSN at least until a new firmware comes out, so you can buy digital games you want, upload trophies, and try PS+ if you're interested. You can activate your system without any hassle and you don't need a PS3 to transfer the game to exploit. Once you're hacked, you'll still be able to run PSP ISOs and
a bunch of emulators. Sure, Rejuvenate might offer a little more in the future, but I think the PSP-mode hack gives a whole lot on its own.
And between your two listings in the first post... I would go for the first one with the bigger memory card. Vita memory is expensive and very valuable if you plan to store PSP ISOs or digital games. Used games are fairly cheap, with both Uncharted and CoD going for < $10 each. (Also, from what I've heard, the Vita CoD was pretty sub-par.) Of course, that's in the US... Don't know what the prices are like over there.
