The 38 Citation is a nice sailing boat and an excellent value and fairly fast.
No...this is not a blue water boat and yes... she is fine for lake Michigan provided you get a good survey and engine analysis. Pay particular attention to the tanks if they have not been replaced.
I don't think Irwins are any better or worse than the other production boats of the era and if their QC was spotty...that has likely sorted itself out by this time and a survey will tell you what you need to know.
No longer posting. Reach me by PM!