I beg to differ, Kirin court has substantially better Dim Sum. I do agree that Arc en Ciel at time did have the best.
Best Dim Sum Sunday Dallas 2006 - Arc-En-Ciel
This Vietnamese-Chinese spot packs 'em in on Sundays for an endless parade of carts that offer a huge variety of dumplings and other dim sum treats. Steamed pork buns, barbecued ribs, shrimp rolls and small plates of ever-changing delicacies make Sunday brunch an adventure. Arc-En-Ciel serves dim sum daily until 3 p.m. but really draws people on Sundays. Especially in evidence are people from the local Asian community. Sometimes there's a bit of a language barrier with the waitstaff, but they are friendly and enthusiastic. If you're not crazy about one cart's offerings, another will be along in two minutes.