I've helped many of my tutors t3bc in the past, giving them 7b, it would cost me roughly 11b if it was done right. So I would say if it's done right, 60-70% is a good assumption. So 6-7b Mind you this I haven't done for close to a year now.
You can never overcome the 40% loss when you drop the tutor, so your transfer will never be more than 60%.