Custom horse conformation

Is it the same or better than a regular EC horse? If better, roughly how much on average (% or whole #) above EC horses? 

^{Custom horses have better chance of a higher conformation than EC horses, I believe it's within the 56-65% range or all goods, those are what I've seen in my own custom horses. Take these two for example - Heaven (64%) & Wire (56%), both created at the same time.} 

Thank you, I think I'll give it  try :)