Hi,
Typically, the stability of the shoal keel version of any model is the same or very close to the stability of the "standard" keel. To get the same stability, the designer shapes the shoal keel to be thicker and/or longer to get the same amount of ballast in a not as deep volume. Often, the shoal keel model will be slightly heavier. On larger boats with internal ballast, the designer may remove some internal ballast to account for the heavier shoal keel. The shoal keel has slightly higher drag and less lift that the deeper keel. I should add that this all applies to a modern fin keel like Bruce King gave to most of our Ericsons.
Performance is very similar under most cruising conditions. Racers notice a slight performance advantage with the deep keel because they are going mostly upwind and downwind on the race course and they are trying to get 100% performance all the time with a full racing crew. The shoal keel may reef slightly sooner. It will be slightly slower upwind and probably point slightly lower. It will be very slightly slower downwind in lighter wind. A cruiser rarely pushes the boat as hard as a racer or sails hard upwind or in very light air downwind to notice any performance difference. The safety and stability factors are essentially the same. I wouldn't blink at sailing a shoal version of any Ericson offshore vs the standard version.
With any luck someone here that has owned both versions of a model will chime in with a comparison from their actual experience.
Mark