It probably depends a lot on the individual instructor.
As was said, balisongs are illegal in many places and IIRC illegal to import, so not many people have them these days.
It is probably different in the Philippines, last time I was in Manila, for example, Balisongs were sold all over the place, in malls and street corners, so they are very common.
I bought a book while I was there, titled "Presas Style and Balisong," which is the best FMA book I've seen.
IMO for practical purposes a modern tactical folder is better than a balisong, though the balisong's lock is superior.