I don't know how to generate the report your asking for, but possible I presume, since the information is in the metadata.
But your request doesn't seem efficient. The last modified date won't tell when a report was last used, just when someone changed anything in it's metadata/layout etc.
You'll be better off collecting information from server logs where user and performance stats are collected.
If you're not migrating tomorrow, turn on more detailed WRS logging:
http://support.sas.com/documentation/cdl/en/biwaag/63149/HTML/default/viewer.htm#a003050065.htm#a003...
Otherwise, migration itself usually isn't harder with more similar objects. Perhaps you could migrate all reports, then use the Environment Manager in 9.4 to get any necessary usage reporting.
Data never sleeps