Personally since about May, on a single hash board. At that time I needed to transition to another unrelated project and promptly forgot all about crypto for a few months. flexmeister wasn't the collaborator I was originally referring to and I'm guessing only for a few days for them since their solution seems to use the same firmware & sgminer that I posted, if I'm not mistaken. Here's a screenshot of the Groestlcoin network hash rate around that time:

Sure thing: https://drive.google.com/open?id=1c6klf2gfuawZqOiOC7cHuWijc_iUxqXc . I apologize for not having the time to do this earlier.