I would assume that the devil is in the details concerning a "replacement".
(my less than 2 cents follows)
Danny takes great pride in these little details which is what makes his speakers so good.
If you followed the Serenity Super 7 thread, it got to the point where somebody broached the topic of a DIY version (which DR wouldn't do as a direct competitor to Serenity). The idea was floated of just figuring out the dimensions and buying everything. While you certainly can, it's the testing and getting the parts modified and matched that is key. A given driver may have similar, even very similar, published specifications on the surface. The problem is, they roll off at different rates, impedence changes over these frequencies, and this must be planned for and addressed.
If you took a different driver and just "dropped it in", it would sound different.
There may be a way to get a different driver, analyse it, figure out what changes would need to be made (milling out the back of the coax driver and the specifics of that, the crossover network, baffle dimensions, etc.) and get something that sounds very close. It might be a little bit better, a little bit worse. Tough to tell until the actual work has been done. Potentially a LOT of work.
A business decision has to be made as to whether or not there's a decent market. It sounds like at a minimum, the BMS drivers would cost more. It might take even more expensive capacitors to make them "sing". This will result in a higher cost for the kit. Will it sell?
(IMHO, probably yes, as it would still sound better than anything else near the current Super-V price, but it is somebody else's call

)