Atlantis for Mac now has many new conversion modes available now in Release 2.2.
It is now possible to convert 1080i50 or 1080p25 to 1080i60 or 1080p24, and vice-versa. Also 720p25 can be converted to 720p24 and vice-versa.
If the compression format is DV, DVCPRO, DVCPRO50 or DVCPROHD, Atlantis automatically selects the corresponding 50Hz or 60Hz compression format as appropriate (provided the Apple DVCPROHD codecs are installed).
A table listing all the possible modes is here.
This is a free update to all existing Atlantis users. To get the update, go to the DVFilm Update page.