I have personally bred Arab X Trakehner two times. The nicerst filly was by an approved Trakehner stallion, and out of an ATA PSB approved Arabian mare. That particular mare had had a couple of very nice Trakehner/Arab foals. I can dig up photos if anyone is interested. She sold before she was even weaned, and for very good money. I think when it is done right, it's a fabulous cross, and that particular filly was eligible for inspection into the OSB, due to her dams' previous PSB approval.
The other filly, out of a VERY nice Trakehner mare and by an Arabian stallion is also very nice, but she was more "arab-y" than the other. A bit too refined for my tastes. She was eligible for insp[ection into the PSB, due to her sires' approval status (unapproved Arabian stallion).
Proud Breeder of Trakehners and Anglo-Trakehners