I'll absolutely stand by this having first off used an X9000 for a month and then not long after a X7000 on my 150" for a couple of weeks. There is no way known, I'd been able to say the cost difference between the two is worth that. I was just lucky that my 9000 was the first purchase (at a great Aus price) and the 7000 ended up a fill-in during the 9000 firmware bungle and became a VW95 replacement at my weekender. Both units will cover you for the screen size, the only caveat I would add is hopefully your room is fairly dedicated and you aren't trying to compromise with any ambient light - not that many would be by the time you reach that screen size. You'll also definitely as Al says, be pushing quite hard at that screen size for satisfaction with HDR in UHD -I'm still at it fine tuning every time I watch a UHD disc but also bearing in mind I'll be making a jump to something new again post CEDIA.
Also, enjoyed SvB a couple of weeks ago when I got to view it, a lot more enjoyable film than I had been expecting by the reviews. I agree with others that it was definitely dark in the context of HDR too - I kept adjusting across the film.
@grassy this is some good feedback form oz here. invaluable I think from someone who has owned both