I'm not as seasoned as some of the members on here, as I'm mainly Nintendo, and perhaps that's why my answer to this thread is...none. All of the cabs I have sold I have had zero regrets selling. My decisions to sell have all been related to space constraints in my arcade, whereby something I wanted more than the cab I was selling was going to take the space. So a 1 in, 1 out situation, where the incoming game I felt was always better than the outgoing one. If I was in a financial situation that forced me to sell, my answer would be different. Fortunately, that hasn't happened and I hope it never does.