The shift points would change, for one thing.
Also, you got close to twice the reduction...the engine doesnt have to work nearly as hard and there is that much less work to do...It will putz around anywhere fine with very little juice and as soon as your on the throttle its making peak power very quickly, so your gonna get a real huge surge of torque seat of pants right there.
My granny low nv4500 is godlike, 4 low is stupid low for anything but rockcrawling which no ifs gm is about to do well.