I have found the M$ registry hack for both recent files and recent places in 2010. I found 50 'files' listed in the Excel reg file folder although the programme interface had been at 'max 5' for a week(!). I also found 25 files in the Word file reg folder although again it had been at 5 for several days. It looks as if Office is not clearing the file cache when the limit is changed.
So far while not quite normal, save as has improved.