I haven't seen those UST projectors live yet, but I own an LS10k and I am sure I would not trade my RLCD against these UST.
The EH-LS10000/10500 are "pro" home cinema projectors from epson, while these UST projectors are not really made for a home cinema experience.
4K alone is not worth it. The LS10k offers much more with it's RLCD technology, superb blacks, settings and options. In fact I love it so much that (in terms of prices) I wouldn't even trade it in for a Sony 760, as the step ups are to marginal in terms of overall quality.
Epson EH-LS10000, madVR on GTX 1080, Oppo UDP-203, Oppo BDP-EU93, Toshiba HD E1, Dreambox 900 ultraHD, Xodiac masked, AT, 3m scope (2.40:1), Marantz SR7011
3x Klipsch PRO-7800-L-THX, 6x Klipsch PRO-7800-S-THX (Dolby Atmos setup, 5.2.4)
2x Velodyne SC-600IW, Velodyne SC-602
Middle Atlantic Rack, RTI XP-6 control processor, RTI T2x remote, LUTRON Graphics Eye QS