There are what I've come to call classic RY4s and custom RY4s. The "classics" tend to be Chinese, either in literal origin or replication and share a similar flavor profile, while the "customs" tend to be American, and are all over the map in terms of ingredients and flavor.
BWB RY4 was one of the first custom RY4s and has a huge following of vapers who love it. I don't personally think anything resembles BWB, although certain custom RY4s may lean in a similar direction. It's not just Don's tobacco base (with its cedar tone) that makes it different, though---his vanilla flavoring is also quite unusual, making BWB RY4 relatively unique and certainly distinctive.
But then, so many custom RY4s are currently available (with more coming all time---now many vendors are offering two or even three different "versions" of RY4), and the flavor envelope is being pushed out so far, that the very idea of defining what constitutes an RY4 is becoming more and more difficult. VapourWorldUK in Britain seems to be the king of RYs, offering 15 different formulations, all of which are variations of a theme.
I just got some RYO4 from Mom&PopVaporShop, which is their third RY4, all of which use a Tobacco Absolute extract base. I like all of mom&pop's RY4 recipes, but---too my palate---they share nothing with the cedar-woody tobacco that Don uses in BWB RY4. They're also darker (in flavor) and have more throat hit than the brighter tone of BWB RY4.
I agree that the OP would be well-advised to buy a gallon of BWB RY4, or, more realistically, as much as possible---and do it now.