Yup, the woodclad is just a 1/32" thin layer of mold food, the fiberglass itself is just fine. If asking window folks for a doug fir interior they'll often try to steer you this way. If you're talking paint grade interior, no reason not to do the all fiberglass unit.
The Marvin Integrity windows are worth looking at, a fairly happy medium. Interior is pine, exterior is a colored fiberglass cladding.
If you want clear doug fir interiors, look at Loewen Windows.