I just sent a message to Rythmik and will post the reply.
It's interesting to me since my main speakers are GoldenEar Triton Ones. The woofers and passive radiators, crossed over at 100Hz by a passive network, are powered by a very powerful amp with dsp response shaping. There is a lot of bass energy available. How to apportionit is a question. Dirac does give the interesting ability to look at the individual response shapes and then separately pick the low and the high pass frequencies. These do not have to mesh together at the same -3dB point. Given that there can be many different speakers involved, Dirac has a lot of behind-the-scenes computation to do. Wish I knew more. I am using Dirac Live 2.4.0.
Dirac replied to my first inquiry, but not to the follow-up questions. My questions : How does Dirac handle a situation in which there is overlap between sub and mains? That question is answered below. Does Dirac recommend the user creating a standard crossover (high-pass and low-pass at same frequency) or would overlap be a possible improvement. This question was not answered.
The GoldenEar mains have a lot of LF power available, as do the two Rythmik L12s. Wouldn't it be somewhat plausible to run the L12s up to their 90Hz limit and th GolderEars down to 30-40Hz? (The woofer section is separated by a passive crossover at 100Hz and has a claimed 1600 watt digital/dsp power amp.) Since they will be in different parts of the room, different modes will be affected, which to some extent might be easier to compensate for.
Dirac's response: the current Dirac Live time aligns the sub output to be sync'ed with that of the mains, which can be separated spatially. Where there is a frequency overlap, the algorithm "will have to choose a compromise." This makes sense to me, since no crossover is close to a brick wall, and the center and ambience speakers overlap 90+% with the mains. This answer suggests to me: try the different options and see. Which I will do, wishing there was a way to measure good, better, and best in a room with 11 speakers handling different music and recordings. Designing the Dirac software must be very interesting.
Dirac's rep added: the new Dirac Bass Management capability will "correct the interaction" and manage the crossover between the main and sub channels.