Do you know how many different "BOM BOS" interfaces are delivered by SAP? According to my analysis we have three as part of these solutions:
SAP EHS Management Classic
SAP Product and Reach Compliance Suite
Component Extension for SAP EHS Management
If you would add SAP Recipe Management then may be we can say: there are four "similar" solutions.
Any of them does have some benefits. At least you can not use them at the same time. This is confirmed by SAP regarding the first two (there is a corresponding OSS note available; check e.g. http://www.stechno.net/sap-notes.html?view=sapnote&id=1404115)) and I assume the same is true for the last solution as well.
How can you use these solutions? The answer is: if your company is mainly "mixing" chemicals without chemical reaction the use of BOM BOS interface can help you during the maintenance of the data. The "BOM header material" will be linked to one REAL_SUB; the BOM items as well to REAL_SUBs and in doing so a "BOS" is generated. Now if you properly prepare a set up of e.g. the classic BOM BOS interface you can run rulesets based on the data maintained on the REAL_SUBs.
The whole topic depends on the strategy how you would like to use this tool/these tools or precisely how you manage your material master in combination to REAL_SUBs. Using BOM BOS it is not easy to "combine" many materials to the same "chemistry" to avoid generating too many REAL_SUBs.
Some discussion are running in this FORUM regarding BOM BOS interface. Most of them are related to SAP EHS Management classic interface. I assume that the "roll out" (that means more and more companies wil may be use this solution) of "Component Extension" solution might change this.