My pair (ETRS and ETRSi) both had the WLF in the kit. I find I use the prism only for portrait sessions, WLF for everything else. Having one less mirror/prism in the way makes the viewfinder nice and bright, and the pop-up loupe is perfect for focusing with my tired eyes
I can't imagine have a Bronica without the WLF. Shame they got tossed/lost/expensive.