I used a sub-1.0 gain (grey) screen with a high-lumens projector for years with excellent results (I removed it from my sig a year ago: Optoma HD65 projector with a Da-Lite Hi-Contrast screen); it definitely improves the perception of blacks with front projection. However, since I got my OLED and it's "perfect blacks", I haven't watched a single movie with my projector!
Yamaha RX-A2050 AVR (5.0.2)
(4) Polk Monitor 10B's (R/L F/R), (2) Polk Monitor 4's (TM), Polk CS300 center channel
Analog: B&O TX2 Turntable, Nakamichi Cassette Deck 1
Digital: Pioneer CLD-99 Elite LD, Panasonic DMP-UB900 UHD Blu-Ray
LG 65EF9500 4K OLED