The guy you runs the yachtsmart.net brokerage has an Irwin38. I have an Irwin 44 for sale and we went from Maine to the Bahamas on her and she was a great coastal cruising boat.
The problem with 70-80's Irwins was inconsistent build quality due to high turnover at the yard...hence all the stories you've heard. As a practical matter...most of this stuff was peripheral and has been dealt with by subsequent owners. I invested a bunch in my boat to make her cruise ready and never had any qualms about her for her intended use. You may find more info on the irwin e-mail list here on sailnet OR you can go to
http://www.angelfire.com/fl/irwinsailboats/