Hytrel is a great plastic, have used it extensively in snowboard bindings. Super performance at low temps.
The TPE material family is made from adding oils to plastics to come up with something in between, I have seem some disastrous formulations of TPE in China factories, looked great and felt great at first, one year later, literally crumbling apart.
With actual Hytrel I had the bad experience in Italy of possibly overheating the material in the injection phase and at -20 C when the product was tested, 100% of the toothed ratchet straps on bindings breaking. In production, no such problem. (lots of transitions and radii added )
Like iab says, nothing beats the range and feel of silicone, and it seems to be a more monolithic chemical formulation to get plasticity. ( assumed)