The various twelve-step fellowships have a lot in common, but they're also distinct. Having experience in one does confer transfer credits.
When I was new in AA, I was encouraged to sit quietly and listen. I think that's still good advice, both for new people and people considering switching fellowships or attending a meeting of another fellowship.
I was at an Al-Anon meeting the other day whose topic was doing service in Al-Anon, as part of Step Twelve, and attendees were welcomed to share their experience on the topic. Obviously, the only people able to take up the invitation were people who had experience of doing service in Al-Anon, whether sponsorship or service within the group or structure. Someone who had not been to an Al-Anon meeting before was very miffed that we did not want to hear his views on the topic.
Al-Anon tends to get newcomers who have undergone psychotherapy or attended other twelve-step fellowships, and such newcomers, even at their first meeting, sometimes share what they have learned from their therapist or in other venue.
Al-Anon, however, is not a pot into which anyone may deposit whatever they want. It is a fountain that overflows into the lives of the people who attend it, and the fountain is constructed from the Al-Anon experience of its members.