Report compatibility between Crystal Reports XI, 2008, and 2016

We have a client that uses Crystal Reports XI (v11). We are delivering a set of reports to them that we authored in Crystal Reports 2008 (v12). Would they be able to safely modify these reports using Crystal Reports XI?

If they purchased Crystal Reports 2016, would they be able to safely modify these reports? Has the report format changed at all from XI through 2016?

Thanks!