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This is often a limitation of the device rather than the technology. Good bluetooth implementations are very rare.
Also, BT shouldn't be viewed as a replacement for wires. I would imagine something like this would be useful for transferring music to/from one iPod to another, or for transferring music to/from another PC when cables aren't available (at work for example).
Hmm, that's an interesting point. I've never used a device that was fast enough to transfer large amounts of songs but I guess it would be theoretically OK. Personally I still think Bluetooth would be pointless, especially with headphones. As an audiophile it would just be a waste of money, because I would never use the bundled earphones anyways. It's sort a niche feature I think. If you wanted functionality in terms of sending/receiving songs then WiFi would probably be the better choice, since you could incorporate a lot of new web-based features later you'd have a lot of options, where Bluetooth is substantially more restricted. Maybe you could beam tracks to a car stereo with Bluetooth?
Yeah, I'm just ranting now.