I made a weight change of less than that before. I had a Lemond Zurich for a couple of years. Steel bike just over 20 pounds. When I put the pressure to the pedals, especially on hills, the frame would flex. Sold that and got a Giant OCR C2. The seat stays were wider across horizontally than vertically, which is supposed to soak up more road buzz, but on hills that rear triangle didn't move much, and I could feel it on the hills. The difference in bike weight was just under two pounds, but the frame made the difference. The wheels were similar stock wheels.
Put your Bianchi wheels on the Kestrel and give it a ride.