From what I know of sub design, whether a sub is horn loaded, front firing or down firing, would not make it more or less 'musical' as long as the driver and cabinet are matched properly. Actually, I don't particularly like that term because it sound so much like mystical.
The actuall driver design will affect accuracy as much as cabinet design. If your driver is not linear, it will not sound as 'musical' as a more linear competitor, all else being equal.
The one exception to this is that sealed subs tend to produce more distortion, particularly when they are driven hard. Its hard to tell when distortion becomes audible though other than to say that we are much less sensitive to it at lower frequencies.
