The BALANCE Dressage saddles are made using either a Show Bar, which sets the position of the stirrup further back than on the GP or Jump saddles, or, on the Xtreme Dressage saddles, the hanging e-bars are set slightly further back, but are not as far back as some riders have come to prefer in a conventional saddle.
Carol and Lesley, who have designed the saddles are both trainers and riding teachers.  They developed a strong interest in, and studied,  rider bio-mechanics as  well as equine bio-mechanics many years ago, and they could see a lot of problems in saddling were being caused by the trend towards riders being encouraged to ride with their stirrups very long and with very little angle in their hip, knee and ankle joints.   This position is much easier to adopt when the stirrups are set further back.    However, this position can be very stressful on the human body when riding in a saddle that is the shape and width needed for a healthy, well-muscled equine back, which is always wide. So, horses have often ended up in saddles that are too narrow for them, in order to allow their riders to adopt a straight legged position.
When you see someone riding a horse bare-back, you rarely ever see them riding without a good degree of angle in their hips and knees.  They naturally adopt a balanced and organised position.  Riding in BALANCE saddles is more like riding the shape of the healthy horse without a saddle and for that reason, the stirrup bars are positioned to compliment this organisation.
(A note from Keren Morris, BALANCE Saddle Consultant... "I can remember riding in a BALANCE saddle for the first time… I was so used to forcing my hips open and legs down and back, because this is what I had been taught, but once in the BALANCE saddle, my legs ended up way too far back!  It turned out I  didn’t need to struggle or work hard, just letting my legs hang where they did naturally put them exactly where they needed to be because the saddle was in balance and supported both my biomechanics and that of the horse."