Frame cracks on the Model 12 occur rarely when barrels are over-clocked during factory assembly. They are not caused by firing +P ammo. These days you are more likely to find a barrel not drawn up, which is an off-shooter because the front sight is not top dead center. This is done purposefully to avoid over-torquing. Windage on a light frame is not corrected by turning the barrel, but by dressing the side of the front sight to reduce width slightly on the side where you wish the POI to move. A 0.010 mill cut on a 2-inch barrel moves POI about 3 inches at 25 yards.
Firing +P in excessive amounts increases wear and causes the revolver to develop end shake. Best is to limit +P for duty carry only and to use standard pressure loads for training and practice. Back in the day the lighter alloy frame gun was carried off-duty and for backup and a steel frame Model 10 was the primary.
Firing 100-200 rounds or so of +P spread over the entire service life of the gun is a non issue. This presumes keeping a shooting log of type and number of rounds fired, armorer inspection during annual requals and making adjustments if needed.
DO avoid the +P+ Treasury loads.