Have you taken a look at admissibility-based transformations (ABT) [1]? It seems to solve the issues that concern you (validating the correctness of OT). [1]

Have you taken a look at admissibility-based transformations (ABT) [1]? It seems to solve the issues that concern you (validating the correctness of OT). [1] http://portal.acm.org/citation.cfm?id=1713726 http://portal.acm.org/citation.cfm?id=1713726