According to our local gallery, the white seats have held up well with many people sitting in the vehicles in the store.
And we haven't had any issues with the white seats in our 2 year old S and 1 year old X.
We do have large white bath towels that we'll throw over the seats when our clothes may be damp or dirty - without anything covering the seats (they look too great to be covered) the rest of the time. And our seats are still "ultra white".
Recommend you check with a local store, gallery or service center for advice in cleaning your seats - and consider using a towel or something else as a temporary cover when you're concerned about transfer.