As the name says, the release candidate is never ready for production. But Bootstrap 3 seems to be scheduled for August 19, 2013 (see http://blog.getbootstrap.com/ ). The first mobile strategy is not an argument for choosing the reason why TB3 also has it now.
Make a list of the differences between the two structures and compare them with your wishes and possibilities.
Zurb Foundation / Twitter Bootstrap 3
Open Source MIT / Apache 2.0 License
Sass (SCSS) / Less
Foundation-icons / Glyphicons
Javascript Components / Javascript Plugins
etc..
Good luck.
PS @Draconar, , , TB3RC1. RC, . , TB , , - .
, ZF Twitter Bootstrap 2.
Twitter Bootstrap 3 Twitter Bootstrap 2, .
, , TB2 .
, ZF, .
: Zurb Foundation 4/Twitter Bootstrap 3