They are designed to keep the rider in place while working cattle, not to provide balance and comfort for miles and miles. Roping saddles are even worse in this respect. Another flaw of Western saddles is that the rigging is too far forward, contributing to girth soreness or galls. Again, the heavy double-rigged roping saddle is the worst of all in this regard. Finally, the saddle horn, necessary for roping, just gets in the way on endurance rides and is a hazard in a fall.
English saddles are lighter and put the rider's weight more forward than Western saddles.
They offer closer contact with the horse than Western saddles, but riders sometimes feel less secure in them. Some English types are more suited to endurance than others. Australian stock saddles have a strong following. Most of these are high quality, give the rider a firm seat, and seem to work well for endurance riding. However, many are quite heavy.