DB - do you know what the g limits for your helicopter are?
Is there a specific warning in the RFM about negative g? (other than for Robbies)
You can get negative g in turbulence - does all the fuel and oil disappear then?
No-one has suggested anyone tries this, it was a question worth asking and answering.
Most manuals will prohibit aerobatic maneuvers, they don't go into much more detail, it's not what civvie helicopters were designed to do.
It also looks quite dull, even with Chuck whatsisname in the 105, it's the wrong tool for that job.
If "pulling g" is the objective, choosing rotorcraft will prove disappointing.