I believe that the BAe146 / Avro RJ demonstrated a slight difference in stall speed with gear up/down (1-2 kts). With the gear doors extended they trap an aircushion under the centre fuselage and the horizontal parts of the doors act as small ‘bi-plane’ wings.
In addition, with a power-on level stall there was a small lift increase due to a recirculation effect over the wing/flap from the increased thrust.