Without going back through the thread again, I know I read it somewhere, and it's mentioned here too:
New Epson Home Theater Projectors Do 4K and HDR Starting Under $3,000
I'm pretty sure I checked specs for both somewhere and found no mention of support in the 7300 but saw it in the 9300, along with things like a second iris and an ISF mode. Of course we won't be 100% sure until someone gets a hands on review and can confirm things - it was incorrectly stated in a couple of news items elsewhere that these were using the same reflective technology as the laser LS10000 but that isn't true unfortunately.