EMB-505 Captain reported control-ability problems and a suspected fuel imbalance while ferrying an aircraft for a maintenance issue. Crew felt the aircraft needed a more thorough evaluation prior to flight due to issues encountered.

Narrative

We were performing a special ferry permit flight to take the aircraft to ZZZ for maintenance following a repeat CAS (Crew Alerting System) message issue. We experienced a moderate flight controllability issue as soon as we became airborne. The aircraft was difficult to control; taking an abnormal amount of aileron and roll trim to maintain wings level. Nearly full aileron was needed in the landing flare (highly unusual even with the 8-10 kt crosswind we had). We believe the fuel quantity gauges were inaccurate and we had more fuel onboard altogether; and much more fuel in the left wing than the right wing. We were never able to get the suspected fuel imbalance solved during the flight. Once on the ground in ZZZ; we notified Maintenance Control; Chief Pilot; and Local Authorities of the issue to debrief them and voice our concerns regarding the flight. We also added another write up in the logbook detailing what happened and all the events that took place to the best of our knowledge/memory.Suggestions: We suggest that go through the high lest level of Test Flights prior to returning to service. We also suggest that any time a ferry permit flight is needed for a FUEL 2 LO LEVEL CAS message; it should be a high level Test Flight; not just a ferry permit. A Flight Test pilot should have done that flight instead.