LawTunes
Intrigued by azslow3 statement: "For one DAW there will be better option then OMF. If you are not in a hurry and you have not decided which DAW you are going to use, just wait 1-2 weeks more."  Can you elaborate?

The beginning of the story: http://forum.cakewalk.com/FindPost/3719945
The plan for "1-2 weeks": http://forum.cakewalk.com/FindPost/3723742
And if you want to know updated status for today:
+ the converter is in plug-in format (Windows 32/64bit, Mac version is not planned since I have no Apple)
+ timeline (tempomap, time signature changes) in place
+ "basic" MIDI clips are in place (grooved MIDI clips and step sequencer clips are imported as "bounced" for now)
- audio clips to go (a must for the first version)
- something from the optional list (may be)
 
So in short, at the moment the result in Reaper is like from Sonar MIDI export. Still without some event types, but preserving original clips position/name and no need to start Sonar for export.
The "beast" is 50kB in size (for clarity: all required information is parsed inside current version, including routing, sends, FXes with corresponding presets, clip and track automations, drum maps, etc. Current task is to "print" at least something from that the way Reaper understand. Since Sonar and Reaper are significantly different in almost all tiny details, that is not as easy as someone can think)

Ive successfully worked with OMFs for years.  I would score an hour long TV show, mix down stems (usually 8 tracks), remove all the silence, then generate an OMF to be sent off to be mixed in ProTools.  Keep in mind OMFs have a size limit...I think it is 2 gigs.  Sometimes I will get a "fail" message only to find the OMF generated fine.  You have to do a lot of experimenting with the options to find a way to generate an OMF for your particular situation.  Once that is done I can guarantee that SONAR will create rock solid OMfs.