yes I have tested this, it is particularely notisable during landing, 1) loaded the plane up to mtow of 4407 and took did sevaral stall test inflight, normal behavior and audiable stall warning before stall, landing as normal. 2) loaded plane to mtow of 4705 lbs, which the sim give a overweight of 343lbs, took off almost as normal (take of speed + 80knots), but stall in flight take place at 80-85knts and somtimes the plane stalls without audiable warning, this is particularely noticeable during landing where you can stall around 85-80 knots. which is particularely anoying if you use the p34 in a fleet as part of the Onair or Airhauler where stall in flight is given a large penalty.
I invite others to do the similar tests.