The short answer is no, I would not buy an older unit.
To draw it out. I have your layout. A 2 month Christmas layout. My reason for buying new was I didn’t want one more thing to troubleshoot. I also didn’t want to risk buying it and then spending full price on the new one anyway. I’m glad I did. There is enough to troubleshoot when DCS is working properly. You’re saving the price of a few boxcars... IMO, it’s not worth the risk.