Brian,
There are two different issues here.
1) Can a DSS plate be used with 3rd party wings?
In most cases yes, and if one really wants to use a STA there are almost no plate and single wing combo's that won't work. For doubles there is no issue here.
2) Will a DSS plate + 3rd party wing work as well, and offer all of the advantages of using a DSS wing on a DSS plate?
The answer here is clearly no. Using a DSS wing on a DSS plate will provides the following advantages; Ease of assembly and dis assembly, least tank offset from the diver, secure direct mount without wobble.
In short using a DSS plate and 3rd party wing is no worse than any other "Franken-rig" but doing so negates many of the advantages of the "system".
Keep in mind that most respondents here have used one BP&W, and as such are poorly equipped to comment on the RELATIVE advantages of any approach.
Tobin