MINIMAL NEED FOR TRIM TABS. You should only need tabs to achieve a level ride from side to side and fore to aft if there is a strong beam wind or there's too much weight in one part of the boat. Long, narrow offshore speedboats, or skinny boats with beam-to-length ratios of more than 1:3, often need tabs for stability and to get on plane faster.
STABLE IN TURNS. At 30 mph, trim the drives for cruising speed with no tabs, then rapidly turn the wheel 180 degrees and hold it until the boat changes course by 90 degrees. According to the American Boat and Yacht Council, this should happen "without the driver's loss of confidence in maintaining control." Try it at increasingly faster speeds. The best boats can do this at wide open throttle, but three-quarter speed is acceptable.
LOWERS GENTLY OFF PLANE. You don't want a boat to immediately lose lift and fall off plane, causing the crew to plunge forward and the bow to dig in and slew around to a new heading.
TRACKS STRAIGHT WHEN GOING DOWN WAVES. If the bow digs into the back of a wave or wake, you shouldn't have to fight the helm to maintain your course. This is a function of buoyancy and hullform forward, as well as rudder size and placement.
SUFFICIENT MIDRANGE ACCELERATION. You'll need this for emergency maneuvers and to maintain control in rough seas. When you hit the throttles at cruising speed (around 3200 rpm for gas inboards or stern drives, 4000 rpm for outboards, 1800 rpm for most diesels), you should feel a noticeable surge.