Shawn: don't stop now!
Clearly the BadJuJu sensor would be paramount.
But even better: do there not exist in the test-pilot caverns some inexpensive forms of vibration monitors? Hi-medium-low frequency sensors for same? A scale precision calibrated in sophisticated units of "acceptable-normal" and "panic-bailout"?
After all, we do equivalent accuracy with G-meters on aerobatic airplanes . . . why not a helicopter shaking-apart measure?
Crowded for panel space? Usurp the IAS meter real estate below 50 knots, the 0-40 k range is useless anyway, as witness your own Bell 206 mast-top spinning sensor!