I think these "open house" things, either with publishers or agents, are a massive lottery. I've tried a few, along with folk from here and from RL whose writing skills I respect, and don't know anyone who has got anywhere. It's not just about being good, it's about chiming with someone who reads the manuscript so that you spark an interest (which depends on personal taste) and then on them also thinking they can sell the manuscript, which depends on trends in publishing etc etc. I think a better approach might be to go to Conventions where you can meet agents/editors and submit that way, rather than as part of a very impersonal slush pile process. Though I'm more and more thinking that self-publishing is the way for me personally.
Another issue is every "open submissions" thing I've done has always massively overrun - one took over a year! Even if you start off a hard-headed realist, and even forget you entered, as time ticks on it's very hard not to get over-invested in it - "Wow I must be in the last handful of submissions now, the deadline was two months ago"- and then feel crushed by the rejection.
I've had some encouraging feedback from some of them, but still, I think I might try and resist entering next time!
Then again, I'd miss out on my virtual chocolate.
Good luck to all and let's none of us forget there are other ways to get our stuff out there!