I agree with Dan and Jim. The tempo varies quite a bit a changes abruptly when the singing starts. However, I believe BIAB\RB can handle this. The hard tedious part will be operator input. I've done this 'vibe' type of song before with success but I don't look forward to it and I'm not volunteering at this moment. ;=)
I suggest creating the tempo map manually using the Click Track option in RB and use Bars rather than Beats. (Image 1 )
For the guitar comp track - I suggest comping the track in this case by:
Guitar generation in Normal
Guitar generation in Half-time
Guitar generation in Holds
Apply the Time stretch/Pitch shift tool along with placing holds at difficult sections if necessary (Image 2 )
If, your SGU commission doesn't require the tempo variances of the original song but to the general feel, complete the project in BIAB and vary between ev and sw RealTracks and 3/4 - 12/8 count. Or alternately, attempt to use the BIAB ACW in 3/4 and equalize the tempo.
Use a sparse bass RT.
Charlie