Well the DSi is a much more drastic upgrade feature wise compared to the DS Lite, the problem is that it also removes a few features and will almost certainly block homebrew out of the box, although it won't be too long before someone finds a way to use the built in SD slot for homebrew. And as for Sony, I think their hardware revisions have been far less useful than Nintendo's, although their software updates are far more useful. And no amount of upgrading will expand Sony's current fanbase beyond rabid "mature/hardcore" gamers who are really just teenagers who want to act cool.
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