Nope, fraid in my view a "normal" category airplane is OK. a full power stall is again in my view a stall and not a whip stall and therefore is within the window of certification for both "normal" and "utility" aircraft. and we are talking cessna's and PA28's here!
Below is an extract from FAR Sec. 23.3 -see item (2)
--------------------------------------------------------------------------------
Sec. 23.3 Airplane categories.
(a) The normal category is limited to airplanes that have a seating configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff of 12,500 pounds or less, and intended for nonacrobatic operation. Nonacrobatic operation includes:
(1) Any maneuver incident to normal flying;
(2) Stalls (except whip stalls); and
(3) Lazy eights, chandelles, and steep turns, in which the angle of bank is not more than 60 degrees.
(b) The utility category is limited to airplanes that have a seating configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff weight of 12,500 pounds or less, and intended for limited acrobatic operation. Airplanes certificated in the utility category may be used in any of the operations covered under paragraph (a) of this section and in limited acrobatic operations. Limited acrobatic operation includes:
(1) Spins (if approved for the particular type of airplane); and
[(2) Lazy eights, chandelles, and steep turns, or similar maneuvers, in which the angle of bank is more than 60 degrees but not more than 90 degrees.]
(c) The acrobatic category is limited to airplanes that have a seating configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff weight of 12,500 pounds or less, and intended for use without restrictions, other than those shown to be necessary as a result of required flight tests.