I use the RF800 with my Elk allowing CHEAP RF controllers to control the sprinklers.
I use the Elk to do the sprinkler control, not a Rain8.
My config has keypad-adjustable twice-daily start times, bypass, and zone durations. It does not have multiple day-per-week options, but I suppose I could add it. I'm pretty happy with it just being one more module on the Elk and control that's then accessible from an Elk, a web browser, ML touchscreens, or an X10 RF remote (which is what I use for testing things, of course).