I'd really like to know who "they" are. I feed all my snakes ASF and have no problems getting them to switch back to F/T rats. It has little to do with the ASF and more to do with just ball pythons being picky feeders in general. If you have a picky snake, it isn't going to matter what you offer it. The type of feeder isn't going to impact its pickiness.
Give the ASF a try.
I see this misconception all the time that ASFs are like crack to ball pythons, but I really have never heard of any study or evidence that suggests that once they have an ASF they will eat nothing else. Probably because it isn't true.