The link you've given does indeed suggest a possible, very mature and eventual height of up to 6 feet. However, every other source on the net says 2-4 feet high and wide, so the odds are with the smaller height. This plant is a cross between B. smpervirens and B. microphylla koreana, and the latter is a dwarf version of Buxus (Box) - it is a relatively slow growing plant, so even were it to make 6 feet, it might take twenty years to get there.
If you really want this plant as a privacy hedge, I think you have to accept it's not going to get the height you want in any useful timespan from a privacy point of view.
Your USDA zone appears to be 7a or 7b - have you considered Lonicera nitida, (the yellow leaved version is sometimes called 'gold box honeysuckle') which is hardy down to Zone 6? Although it's one of the honeysuckles, this one is not a vine, but a free standing, small leaved shrub which responds well to clipping - it makes a good, low, evergreen hedge, usually up to 5/6 feet for the yellow variety. There is a variety with green leaves; 'Baggesen's gold' has yellow leaves, and there's a newer variety called 'Lemon Beauty' with variegated green and yellow leaves. Its use as a substitute for box hedging is becoming more widespread because of the disease problems with Buxus varieties.