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on a second thought, the speed of GOTO mounts is limited and for your type of work only alt/az (fork) mounts come into play. For a helicopter I recon none of the existing mounts are fast enough and since you need to lock the autoguider first on your target by manually following your target, the mount hasnīt really got a chance to give you some staedy views for shooting (not to mention the time required for accurate focusing) before the target (be it plane or helicopter) has moved out of reach.
The ISS is more predictable as it follows a fixed trajectory undisturbed by atmospheric conditions (like airborne targets) and it moves rather slow between the oportunity horizons compared to an aeroplane.
I sometimes tried to follow a plane with my Dobsonian mounted (alt/az-fork) telescope and I only managed to get very brief glimpse at it (mostly not in the right focus).
I think for helicopters and planes you are far better of with a manual solution like a tripod, a DSLR and a telephoto lens.
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