Handling wouldn't be affected much at all with a mild lift. Certainly wouldn't be worse than what the static lift guys get when they lift 2"+, and there seems to be little discussion about ill handling at those heights. Loss of caster (which affects directional stability) is a concern with too much lift, but with 1.25", he should be just fine.
As with the 100-series and an AHC lift, the next concerns would be maintaining max weight carrying ability at the new neutral height. Because AHC now bears more of the weight load to get to the new height, it potentially has less overall load capacity. Techstream should be able to indicate if neutral pressures are out of spec. The way to return the system to normal pressures is to preload the spring suspension more. Likely that toyota shim talked about for the front, and spring spacer for the rear. 80 and 100 series spacers should work for the rear of the 200.
As with the 100-series and an AHC lift, the next concerns would be maintaining max weight carrying ability at the new neutral height. Because AHC now bears more of the weight load to get to the new height, it potentially has less overall load capacity. Techstream should be able to indicate if neutral pressures are out of spec. The way to return the system to normal pressures is to preload the spring suspension more. Likely that toyota shim talked about for the front, and spring spacer for the rear. 80 and 100 series spacers should work for the rear of the 200.