A study of survey responses regarding Specific Language Impairment testing was discussed in the April (2013) Language, Speech, and Hearing Services in Schools. The authors basically found out what tests SLPs were giving and compared those to test characteristics, such as validity, reliability, etc. They generally found that characteristics such as the inclusion of multiple facets, and testing time seemed to be more important in test selection, than characteristics such as reliability, accuracy, and validity. SLPs also like to give single word vocabulary tests. The synopsis is at this link.