Does the Savi® W710/W720 Multi Device Wireless Headset System work ok for people who wear hearing aids

The Savi H710 / W720 can work for hearing aid users, but it is not rated formally as Hearing Aid Compatible (HAC) the way that newer models are.
The newer Savi 8200 series (Plantronics Savi 8210-M and Savi 8220-M are specifically documented as having T-coil support

From Plantronics documentation I can find that the following legacy models are all hearing aid compatible:

Over the Head Voice Tube: Pulsar 590, CS351, CS361

Over the Head Noise-Canceling: CS351N, CS361N, B825 (Voyager Focus), B825-M, Savi 8210-M, Savi 8220-M

Convertible Noise-Canceling: CS50, CS50-USB, CS55

Over the headset Bluetooth: Voyager 8200 UC