Already sounds like great progress! I’m very interested in the seq2seq stuff these days, and I miss customizability in onmt a bit  - I did some efforts, but everything is very interconnected (data and models)) so customization is not very straightforward - so having great seq2seq in transformers would be helpful for me.
About SOTA on summarization; are you planning to jot down your findings in a paper or blogpost? Might be an interesting read!