If I understand correctly, your plane already has both Lemo and GA connectors, and your question is really only about your headset:
— does a headset with a Lemo connector have any disadvantage?
The answer is it has no disadvantage in your plane, based on my experience in a similarly equipped plane.
However, if you wish to fly sometimes in another plane you might need a second headset with GA connectors. I keep an old David Clark headset for exactly that reason. For example when a shop gives me a ride home in the shop’s plane. I use my Lightspeed pfx otherwise and I really enjoy the ease of not fiddling with batteries.