I’ve had my First Gear heated liner since 2003. It has gone through many winters and held up well.
As with anything used repeatedly wear and tear will eventually take its toll.
The weak spot is the DC connection between the liner and gloves. The mono jacks wiring seems to come apart at the point it makes contact with the connector base.
I have enough parts in the Manetarium to replace the worn parts as needed.
The connector replacement wiring I use has a larger diameter wiring and the insulation cover is much more robust than the original.