I've had mine for a little while now. The reason I wanted it was because of the shape of the grip, and it still fits my hand perfectly.
I've shot an Aerotec on a few occasions. The ones with slow limbs - such as W&W Focus - felt okay, if nothing special. The ones with fast limbs - Border ML2s as it happens - where loud, sharp and sent a shock right up my bow arm. The Helix does none of these things; it feels entirely different. No shock, but it still maintains some punch towards the target.