There is also work on how wildcard will be validated. Aaron has posted about wanting an "ADN" to be set by the ACME Client. See: Will Let's encrypt support tree climbing for dns-persist-01 records? - #6 by aarongable
Personally I feel there is enough substantial differences to wait. It is difficult for ACME Client authors to make clear to their users which draft is supported and how things should work. We saw this with ARI, for example.