No problem.
A new version, trial or not, is totally independent from another one, and you can use each one independently (not both at the same time).
Installing the new version will prompt you to 'convert' your current catalog if you wish so. The conversion does not change the old catalog, a new one is created with the same name. The old catalog is simply renamed with a -1 suffix (it is still recognized by the older PSE version). Let's say you do the trial now and only upgrade months later, you can still re-convert the old catalog.
So, yes, to do a good trial, convert the catalog to see how that works. The old catalog will still be sound and available later.