If sonar 64bit do not open 32 bit projects, you can still salvage the audio,midi, via importing all audio and midi regardless,into the new 64bit, so yes save all projects, and see what gives, or you can still take from it, if need be, and redo the mix,effects,mastering..
you can also run 32 bit programs on 64 bit os...so you can run both versions of sonar....