I had one in the early 90s for one or two years.
I used it for triathlon racing only and only for water.
There was no way I was going to put anything with sugar in it and be confident I could keep it clean.
The funny thing I remember was when the bite valve got worn and wouldn't shut off immediately.
You'd get a mouthful of water, and as soon as you pulled your mouth away, the thing kept spraying, usually onto your face.
We called it the "Bikestream baptism".
It actually was kind of refreshing because it rinsed away the salt build-up around the face and eyes.
In fact, sometimes I would bite the valve to get a face shower primarily.
It was an interesting idea for triathlon back in the day, but prone to failure and not useful for long-course racing as it couldn't be refilled or replaced on the fly and had limited capacity.
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WTB: Slingshot bicycle promotional documents (catalog, pamphlets, etc).
WTB: American Cycling May - Aug, Oct, Dec 1966.
WTB: Bicycle Guide issues 1984 (any); Jun 1987; Jul, Nov/Dec 1992; Apr 1994; 1996 -1998 (any)
WTB: Bike World issue Jun 1974.