Andrea,
Avanti is a relative lightweight and more "agile" aircraft when compared with a typical airliner, ie B738, so might "feel" harder to control. Do a test. Fly the Avanti and then the default King Air (C90), since they have a relative similar size. At least for me the response is almost identical in both aircrafts.
Beyond that, even Avanti and King Air have small differences, and with the new XP11.10 the ability to setup per aircraft controls configuration is very helpful. Said that, and given that due to Austin fine tuning the engine simulation from his PT6 engine, almost the same with the Avanti engines, when 11.10 goes final, we will revisit the flight model to do some adjustments, including flight controls response.
Regards