2000 models and on with 64 mb of ram shows slight performance improvements overall for load times in native psp/psx games as well as general emulation performance (CPS2, daedalus, s9xtyl, gpspkai, picos, etc) and other applications that support it (go**be, homebrew browsers, homebrew/ported games, and slim only high mem modded apps). There are other basic features such as Skype that only work on slims as well. I'd go with 64mb slim models over the 1000 models overall.
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