The way I work might be the long way around the block.
I had a song in a certain key that fit the singer well. I wrote it in BB and use RB to render the tracks.... all was good.
For a certain reason, we needed to get another singer to record this song but the key for the first singer wasn't comfortable to the second singer.
I went back to the original file in BB, opened it and simply changed the key to the one the new singer was asking for and saved it with a name that reflected the new key. I rendered the tracks in RB from that new key version. There was a unique difference in the way the tracks were rendered that made this second version more interesting, IMHO, than the first version.
That may be a longer way to the goal line but it certainly works and the instrument tracks do not sound like they were pitch shifted in a haphazard manner.
Just for the sake of curiosity, here are the links to that song and it's 2 versions in different keys:
version 1:
Helms singer version 2:
Rose singer