For growth, personally I prefer megatek. I use P&S to protect the hair from mud in winter and the sulphur is great for skin condition and keeping mites/grease on feathered horses away.
If you do use P&S you do have yellow hair, but it soon fades. The sulphur keeps feather white.
You can use P&S on manes and tail - I have for itchy horses, plus pig oil is a very cheap detangler and in a bit of hot water, a very good coat shine - but only a tiny bit or you get a greasy coat.
With my cob, he has his mane and tail regularly applied with megatek and then bagged in winter to keep the mud off the hair and damaging it.