copy / backup question - copying a data directory while the db is shutdown

Hi All;

If I shutdown a HOT standby slave (via the -m fast command) can I then
copy the data directory to a "backup" location and be guaranteed that
the backup copy will start?

For some reason I thought there were issues (or potential issues) with
this method and a PITR based recovery approach was a better guarantee
that the copy will start


Thoughts?