20-45 degree hills?
That makes my kneecaps hurt too. Anything where my cadence drops below 40 trying to get the pedals to move.
What's the equivalent in %grade?
Have somebody tell you if your knees are bowing out or if they track straight through your pedal stroke.
Moving the saddle forward also changes which muscles are used. My knees prefered having the saddle scootched back.
It does take a while to get used to a new bike fit. Your body will adapt to accommodate a certain bike fit and won't like changing.