I've been riding my two 2016 Radrovers work commuting and trail riding. I usually leave the PAS in 3 for work commuting and PAS 2 when trail riding. I usually try to keep a certain pedal cadence at all times of around 60-80 rpms and down/up shift to maintain that range. I rather downshift and drop my speed on inclines instead of upping the Radrover power levels. I still use PAS 3 (350w-375w) on steepest hills around town and downshift as needed to keep my cadence range.
I do on occasion use PAS 4 on really windy days. Having a +20 mph headwinds on level ground feels just like a steep incline AND much worse once you start an incline. I end up using too much battery power at PAS 4 on those days (maybe get around 12-16 mile range with 11.6Ah battery with +20 headwind+500 elevation gain between work/home).
I sometimes use the throttle if my speed/pedal rpms start to drop near the crest of the hill and I just need a little boost the last 10-20 feet to keep my mph and pedal rpms up without downshifting.