Ok, if you can imaging the living room now converted to a range, we've been doing some positional work
From my point of view. Without jacket and glove, I am able to achieve the same hold in the able and disabled shooting positions. The abled kneeling position is harder to get into because it places more emphasis on flexibility, however I am happier in it (probably due to unfamilarity with the other). With the leg out, the disabled position is easier to get into, but my hold is the same.
With only elbow contact on the knee, the able position is more comfortable, and offers the same hold movement to me as the disabled position with only elbow contact on the knee.
So my thinking is that the disabled position gives advantage only to those shooters who cannot or will not develop their kneeling position to it's true potential, likely to be lower grades. Once the kneeling position is perfected, I see little difference between them. Without all my kit on, I am less comfortable in the able position, but with a bit of grimacing bearing the pain in my ankle on a hard floor, I can achieve 95% of the hold i can in the disabled position. I am confident that on the range, on soft ground with shoes and any jacket on, i'd be just as comfortable.
So, perhaps it just gives advantage to the lower grades, and the more skilled shooters are more comparable.
It could perhaps be said the same as the standing positions... it might allow less skilled shooters to take shots well, but up against a good standing shooter, the difference could be marginal between two skilled shooters of differing physical ability, if any.
Have a go, see what you think.