all still rolling along, page-5

Firstly, the flow for 17 hrs was 1.927mmcfd, not "nearly 3mmcfd".
Secondly, the flow rate was limited to 0.600mmcfd; the announcement gave no indication as to how long this rate was maintained, or how much gas was produced in a given time period.
Thirdly most of the proppant has been recovered - I don't think that there is a "significant" amount left down there.
Fourthly, the possibility, or otherwise, of fully opening the well for max. flow rates depends upon the flow rate. Sure, if this was a 5mmcfd well, not a good idea.
As I see it, they've removed as much proppant as they can with it choked. Now, to get rid of more, they need gas velocity to lift the liquid. This can only be achieved by maximising the flow rate, meaning that you run it unchoked. Hence the rapid build up of flow rate to the maximum after one and a half hours, followed by a decline as the pressure drops. Maybe the flow rate isn't enough to clean it out completely, naturally.
So, on the 10th June they announced 1.927mmcfd in a seventeen hour period. On the 1st July it flowed 0.723mmcfd in a 24hr period, with a max flow rate of 1.684mmcfd pushing against a lot less proppant than in the previous test. This probably explains why the directors were not pleased to announce, and all the confidence about this being a 2mmcfd commercial well has dropped out of the announcements.