Wanted to update this thread.
I did some lurking and question-asking in the JVC forums and came across owners who are indeed using X790R on a 150" screen. The bottom-line undoubtedly stood out that a 4K HDR Projector with more Lumens then ones currently available will be the best choice - however - since there isn't one in the market with those specifications, the better choice still stands at JVC. The Lumens output provided by Epson in literature, which appears to be considerably more then JVC or BenQ, isn't necessarily so in real world.
Neither of the 3 projectors are going to 'Excel' at HDR & 3D on a 150" Screen, however, neither of the 3 is going to provide better/more brightness then the other. That being said, JVC does seem to output enough to project perfectly fine on a 150" screen (which was my biggest question).
Contrast, Blacks & 3D on JVC, from what I can gather, is unbeatable. Epson seems to be the close runner-up.
I really have two choices here:
1. Get the Epson 5050UB now, save the few hundreds of dollars, in a year or so invest in a true 4K HDR which has higher lumens from JVC or Sony.
2. Get the JVC X790R and call it a day.
I'm leaning towards the JVC X790R. Once I get it, set it up, try a few different movies, if I don't feel Brightness, HDR & 3D is working for my screen - return for refund. Go with Epson.
If I go with Epson first, I'll always have the lingering doubt, what if JVC had worked?
So, I think I'm pretty set here. I'm still on waiting list so the purchase is not going to happen tomorrow, but is expected towards the end of this month. If something changes my mind in the meanwhile, so be it.
7.1.4: Polk RTi12 Fronts, RTi8 Surrounds, Monitor70 Surround Backs, CSi A6 Center, Klipsch R-14M Front Height & Rear Height + Outlaw LFM-1 EX Subwoofer.
JVC NX5 True 4K HDR Projector / Denon X6300H AVR
Intel Broadwell-E 6 Core (H2O) / EVGA RTX 2080Ti FTW3 Ultra Hybrid (H2O) HTPC
LG UBK80 UHD Blu-ray / XBOX One X