What lenses do you expect to be using for these astrology shots? The focus by wire is inherent to certain lenses [the "basic" lenses only I think] not the body itself. If you mount a Sigma lens on an Oly body, it will still use the traditional method.
Focus By Wire is just different, and can even have its advantages when you know how to use it right. The gist is, if you're turning the focus quick, then it the focus will jump quickly, and if you're tuning it slowly, it will make much finer adjustments.
Actually you have a point, the lens I'd use for "astrology" shots would be a 2540mm telescope (10"f10). The "focus by wire" concept wouldn't apply then, would it. I suppose the same would occur if one used Zuiko (35mm) manual lenses as well. But it was good to hear the key to focusing accurately by wire is primarily the speed of rotation. I think I understand better now, Thanks!