A Farr hull is a hull designed by Farr Yacht Design, the world's leading designer of racing and cruising yachts. The hull design gives it good performance, stability and comfort.
As for the jib size, recent design trends have led to larger mains and smaller jibs. As you've sailed on a 32 many times, you should know that it performs well.
Your teacher's fondness for the Dufour 34 is only his subjective opinion. If you ask 10 people for their favourite 32-34ft yacht, you'd get a lot of different answers. So you can ignore his preference and make your own decision.