A man named "spyclip" posted this on The Drive. Seems very knowledgeable, probably a former engineering insider at Sikorsky:
Spyclip
1 July, 2022
No vibration issues? Are you serious? The vibration is the entire reason they have flown only a few dozen hours in 3 years of flight testing and only allowed a single sortie flown by Army test pilots at low speed. The AVC system approach has been a complete failure (again, just like S-97), and the dynamics of another insufficiently stiff fuselage for the propulsor drive shaft make the SB1 just as much of a paint shaker as S-97. Pilots can't even read their instruments in these designs due to the vibration. SB1 has hit absolutely ZERO of its own self imposed targets in demonstration. Sikorsky's own target was a cruise speed of 250 kt at MCP, while in the end they could only manage a momentary 247 kt at CRP (130%). Swing and a miss on drag estimates, and vibration levels at high speed put a cap on that. To date they have not demonstrated any Vector Control maneuvers despite touting it in every single mention of the technology. Go watch the videos, there is no level acceleration or deceleration - its always nose down gaining speed like a normal helicopter. And they most certainly have not shown Defiant holding nose high or nose low attitude in hover, much less any ADS-33 level 1 handling maneuvers outside of a lumbering slalom. V-280 demonstrated high rate level 1 hover pitch, roll, and yaw multiple times. Sikorsky hasn't even done a hover pedal yaw turn in Defiant because they have next to no yaw authority with differential torque and it would be embarrassingly slow.
]https://www.thedrive.com/the-war-zone/raider-x-lockheed-martin