Is there any reason other than price that you went with the Parrot kit rather than the Sony Ericsson one? I'm leaning towards the HCB-30 mainly due to ... the fact that it's made by the same manufacturer as the t68i, so it will definitely all work together.

I'd been thinking about this and came to a conclusion. While the Sony handsfree kit might work better with the Sony phone, it's much more likely that it won't work at all with some other phone. That is, what happens when you get a new phone? The Parrot is likely to still work, as it's intended to be cross-platform anyway, but the Sony one has a much greater chance of not being able to.