@xcrossi, no, you will not run into any problems that are major. The only problem you will run into is say you want to download something to your Trainz 2012 CMP. If you had been using your Trainz 2010 CMP, and did not open your 2012 CMP after you were done using the 2010 CMP to download the item into the 2012 CMP, the item will get downloaded to the 2010 CMP. That's the only flaw.