The T-Rex mechanics, after a long period of pause and then some experimentation with tests, has been put back to the fuselage.
Installed new and slightly longer S-profile blades (from SpinBlades and Helicopter Baumann), solved the vibration problems with new small aluminum mounting plates and lowered the RPM to ±1250-1300 in latest (very quiet) test flights.
Also added some 3D-printed (HIPS) plastic top holders for the mounting of the mechanics to further stabilize the upper part of the fuselage (see pictures below - I had also tried the 440KV motor from Align, but I put back the Hacker A50 Turnado at 400KV for lower RPM).
Now, I am waiting the painting of the blades (balck) to dry and aslo doing some checkup of the motor from Hacker before resuming flights...
...and one more from the scale modeling part: a 100% in-house fabrication (from CAD to 3D-printing, hybrid resin and FFD) of the collective lever its gear: