I bought some Fo Shou too. It's used to make Ti Guan Yin.
The smell is very similar to the highly oxidized, deep roasted Guan Yin, but I think it's more close to citrus.
Fo Shou's leaves are quite large. The farmer told me that it will make the roast become more difficult. perhaps that's why Fo Shou is not common in Taiwan oolong.