No worries.

I think they should standardize them. One servo horn for al all servo horns for one ...

I fly planes as well and end up swapping servo's between them if needed. For some reason I tend to go through more planes than servo's I neatly cut off arms on horns that I don't need to prevent them from banging agains something and it looks neater. So I always run out of horns. The ones I had on my heli I also use in my planes and they work fine. They fit snugly, you can feel when you are using the wrong horn on a servo. They iether don't slide on or slide on to easily ...

But I suppose the forces that feed back to servos from a heli doing 3D is much much more than that of a 40 sized plane. At the end of the day I just used servo's that where not designed for such loads.