I've had both the Tekno and Traxxas wing mounts, and I prefer the Traxxas one. It is sturdy, yet flexible, and due to its position doesn't require that you remove a lot of material from the body.
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Well, from the pics I've seen the JConcepts wing appears to be exactly the same as the Tekno wing, so I wouldn't bother trying it out. The Traxxas one sits a lot lower then both of them which, as MetalMan stated, requires less body trimming. But, if it's sitting lower you may not get as much downforce as the air passes over the body.