To me it depends on the cost both literally - what it would cost to modify existing engines and what performance loss against noise reduction gain.
Silent Paramotors are obviously the snake oil as like you said, the prop will make noise but if there is a quieter engine that doesn’t sound like, as someone put it - a dirt bike in the sky for a performance loss I can deal with. I’d be happy.
Would love to jump onboard with electric Paramotors but I feel it’s the same lifecycle as electric cars - early gen will be/are low distance and high recharge time which will both improve with tech.