I am against having a beta flag.
Answers should stay valid for a longer time and such things can change fast. Many programs are labeled beta, but behave perfectly stable (many Google applications for a long time). Others are considered stable but still buggy (a lot of proprietary software shortly after release). There are also programs that worked fine once, but fail in some of their functions now, because they rely on interfaces that have changed (like python libraries or deprecated linux kernel modules).
Possible problems should be pointed out in the text. That way everybody can check if they are likely to affect them. This is much more detailed than a generic flag.