I can't answer for Bansko, although I do have a few former colleagues who work out there who advise there is plenty to do.
As for Borovets: I'm and advanced/expert skier. The terrain is more than adequate for technical training to a high level. Some steeper and often variable terrain is available. There are also several FIS rated race pistes.
Off-piste is not recommended without a quailified guide or survival equipment and only when conditions are deemed safe. Off-piste there is a very ...
I can't answer for Bansko, although I do have a few former colleagues who work out there who advise there is plenty to do.
As for Borovets: I'm and advanced/expert skier. The terrain is more than adequate for technical training to a high level. Some steeper and often variable terrain is available. There are also several FIS rated race pistes.
Off-piste is not recommended without a quailified guide or survival equipment and only when conditions are deemed safe. Off-piste there is a very definite risk of a snowslide - as local history will show.