Just my 2 cents...
I've used azslow3's converter quite a bit and I think it's great.
No, it will not flawlessly give you a tightly organized, elegant Reaper project for every conceivable SONAR project. No one should expect that. Even in the best cases, I get a lot of empty tracks that simply have to be deleted.
But believe me, if you're translating a lot of SONAR projects to Reaper (as I am), it GREATLY reduces the work. I've done it "manually" (exporting MIDI and audio - making sure every audio track starts at the beginning - and importing them into a new project, reproducing the tempo map, markers, routing, effects, and mix... it can be done, but man...).
Respect to azslow3 for putting something out there that could be predicted not to meet unrealistic expectations and draw complaints. It's kind of typical of the Reaper community.
I've still got BandLab's Cakewalk on my machine and sometimes use it to facilitate moving more difficult projects to Reaper. I'll continue to hang on to Cakewalk in hopes that someone will pick it up and develop it (after all, I've been using it since 1989). But Reaper fills the bill for me in the time being.