Betas ONLY apply to your expert account. If you are enrolled in the betas you will only see the betas in sites you create within your account. If you are a contributor, it will not carry over. Likewise, if someone is a contributor on a site that is live in your account they will NOT see the betas either. It is 100% account based.
If you transfer a site - you will no longer have access to the beta because that account is not activated for betas.