I bought a Rosetta 800 for the very purpose of getting 8 more simultaneous analog i/o. Works great with ADAT, but I want to use it with AES at 96k so just waiting for some snakes to arrive.
In the SPDIF RCA port I have a Roland Integra 7 slaved at 96k and it sounds amazing. Much nicer, fuller and crazy sharp and clean compared to the analog ports.
I have used the ADAT ports for testing the Rosetta and ADA8000 and they work seamlessly but only work at 48k or lower. No SMUX for ADAT on the H9000, yet.
I have the Dante card so I get 32 in/out at 96k through the H9000 anytime. I may add another Dante stage box in the future but I dont really need more than the 16 analog in/outs that I have right now. But it is nice to have the Dante card for 32/32 from the box when working on projects ITB.