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Someone should write an article about zooms, because this is a very good question that comes up every so often.
First off, good zooms will cost you hundreds of dollars anyway (Leica, Pentax &c), whereas two or three good fixed focal length eyepieces can still be affordable.
Years ago, cheap zooms were ludicrously long, clunky, and delivered faint blurry images smeared with rainbow colours. Compared to those, today's cheap zooms are excellent, but when compared to today's relatively cheap fixed focal length eyepieces they still perform poorly (IMO). And then, performance aside, the other bugbear is the way the field of view narrows so much as you zoom in that you lose what you're looking at. And they're certainly not parfocal all the way through the range of magnification, so you have to refocus with every change. Easier to just change a couple of parfocal EPs around (and if they're not parfocal, make them so with a parfocalizing ring).
Just my opinion. (I'm not totally anti-zooms. One day I will pounce on a Televue 3-6mm zoom, when the Aussie dollar makes a comeback perhaps.) Maybe try to have a go with someone else's before buying one.
Cheers,
Brian.
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