For starters, Hemlis is not open source. That should stop you in your track right there. If it doesn't, maybe the fact that they actually had to switch to another crypto system for Hemlis after much negative feedback from the community, should tell you more about their experience in this. But even that new one doesn't offer anything resembling forward secrecy. I think Hemlis will be more of a Threema clone, which also isn't open source.
1 - https://missingm.co/2014/02/fighting-dishfire-the-state-of-m...