Is it of any benefit with regard to the representativeness of the sample to further reduce the rate to 100 mL/min. (assuming the drawdown is less but still several feet)?

As long as there is not a stated drawdown limit that you have to meet, stay at the highest practical flow rate. Provided that the water level stabilizes very quickly, the preference would be to stay at that higher flow rate and greater drawdown. But, if you have continued drawdown that will not slow down you have no choice but to back off on the flow rate so as not to dewater the well.