This is definitely dirkhh's call, but in case he hadn't thought of this aspect of this, you may want to check with him one more time before closing it, if he doesn't get with you or respond. My thinking is that leaving it open allows Dirk to see if there continues to be this gap in response, and allows him to attempt to narrow that gap if he chooses to attempt to do so. As you, Mike, or someone else pointed out a while ago, the poll is just a couple of clicks, so it's really easy. Once someone has completed the poll, if they wind up being asked to take the extra step, they may go ahead and do it. But I think if they find the poll closed, they are probably less likely to go the extra mile in the first place. I mean sure, some people will, but those people aren't the people I'm talking about trying to catch. You're going to get those people anyway. The trick is getting those people who were just willing to fill out the poll to go a little further, and I fear if the poll is closed we'll just lose them completely.
Again--definitely dirkhh's call, as he's the one writing to these people, and he may well have had enough of that anyway. But if he's still inclined to write to people, my fear is that once the poll closes he may quickly find he has no one to write to.