I remember those wooden storm windows with plastic sash guides. It was an attempt to give the look of a wooden storm with the ease of moveable sash similar to aluminum storms. However, the plastic became brittle with age. Also, moisture tended to get behind the plastic guides and cause the paint to peel from the wooden frame.

There is much to be said for full storm windows. The amount of dead air space is far greater than any dual pane window can equal. It is that dead air space which is giving the thermal efficiency. They also keep the wintry winds from driving against the primary window.