I had the experience of taking my father who is wheelchair bound and speech impaired through security at DFW, generally i was happy with his treatment which was carried out with proper respect. My only concern was that although i could always see him i had to stand 30 feet away whilst the screening went on, because of his speech impairment he could not answer any questions and although i explained this, i was still not allowed any nearer.
The screener was friendly however and did put my father at ease.