I'm not sure if brazilian rosewood is "better", but it is more historically accurate as that was what was used on real '59 Gibsons. And it's a pretty rare wood from what I understand. Tokai can probably get away with using it on higher end models because their production is so much lower than Gibson. Apparently, Gibson only used brazilian rosewood that can be verified on a few Historic models in 2003. Some argue that they used it on some in earlier years, but there is no verification from Gibson on those. So when you go to buy a Gibson 59 Historic with a verified brazilian rosewood board, be prepared to pay double or more than what a regular R9 would go for because of its rarity.
I don't think I'm sensitive enough to pick up the difference in tone and playability between a brazilian and indian rosewood board. That being said, maybe that is exactly why I like my 320 far better than any historic I've played. Who knows.
My 320 isn't particulary light at 9 lbs., but it is certainly not heavy. But even if I could find one lighter, I doubt if I would replace it. I can get the action about as low as I've ever had on any guitar. The neck, to me anyway, is a perfect size, not too clubby or thin.
Honestly, I can't point to one thing that makes this guitar magical as compared to Gibsons. It's the whole package, it looks right, it feels right, it plays right, it sounds right. It's just the whole package, and it's completely stock. Maybe I just got lucky, but to hear others talk about their 320s, I don't think so. I just think the Tokai luthiers that were building these guitars were in a groove. Maybe they still are, I haven't had the pleasure of playing a 380. Every time I see a 320 for sale, though, I think hard about buying (this one on ebay as well). But then I feel guilty about hoarding it, if I buy it that denies some other lucky player the pleasure of a 320.