Here’s a link to a few of the “beta testing” threads where similar concerns have been talked through before:
In years of authors discussing this issue, I’ve yet to see any evidence of significant numbers of customers sitting out a game because they got to forum test it first. The forum community is a small fraction of the people who buy CoG/HGs; many are predisposed to buy the games they test, as a way of supporting the authors.
Different authors feel differently about the quality bump that comes from developing their games on the forum – but for my part, I’m very pro-forum.
My own game was available in full on the forums for testing for many weeks before its final beta test and release, and still became one of CoG’s bestsellers when it came out.