Yes, the 1.5" adjustment at 100 would lower the 200 yard POI 3" using the same hold you used to shoot the groups posted. The adjustment is to the sight so it will affect all loads the same. If you were holding at the bottom of the circle the adjustment would put you 5 to 6" high with the same hold.

BTW, why are you not using the 200grXTP for all your deer hunting instead of the 300? If you are getting that kind of accuracy out of it and you trust it enough to take a 200 yard shot, why not something closer? I would guess the 6" point blank range of that load would be around 175 yards with it +3" at 100, on at 150, -3" at 175 and be down about 8" at 200. Energy would be down to around 650fp at 200 yards which might be a bit low but if placed right itshould be enough.