Having major problems using Melodyne's Tempo Editor (stand-alone program).  It seems no matter what I import, it never correctly detects the first beat of the song, and even though I've recorded the project with a metronome in SONAR, it adds little spikes and dips in the tempo at various intervals. 
 
The other major problem I'm having is that if I alter the tempo even slightly, it introduces some major phasing issues on the track. Has anyone had success using Melodyne to edit & alter tempos and could give some tips? 
 

It took me several times reading the manual + watching related tutorials before I have managed just extract correct tempo for the first time
I recommend to get throw Assign and then Modify sections in the manual till you understand what every operation does, so when and how to use them.
My major mistakes was:
1) working with tempo editing without checking it is assigned correctly
2) using tempo editing on places where note editing should be used (f.e to change the length of a note).