As a technical rock route's rating informs a potential climber as to its difficulty (& thus gives them an idea of whether or not the climb is possible for them), so does the steepness of an ice route tell its difficulty. This should be stated in the route description, as that the couloir constitutes the majority of the climb. Also, the gully from the other (W) side is class 3, with a few moves of 4.
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From the top of the chimney variation to the base of the U-Notch is a little under 50m, so you can do this in 1 rap if you have 2 50m ropes or anything longer. If you have 1 rope, there are some slings half-way down. In summer, downclimbing the Clyde Variation is a good alternative to rappelling; the downclimb starts at the top rappel slings and goes down the first chute to the West.