When varying the quality of the ASR systems, we found that the CONFIDENCE and CONFIDENCENODUPLICATES heuristics have similar scores, and outperform the ASR only when its accuracy is considerably low; however, in that case, the use of MT alone offers a better option.
a priori knowledge of the accuracies of ASR and of MT leads to simply selecting the output of one or the other, depending on their accuracy, with no need for a combination method.