It does actually say in the book that any race can be a thief-acrobat. I just have a hard time imagining a dwarf tight-rope walking and doing cartwheels to avoid spear thrusts.
It's not a dual class option, really. It's specialization, so it's really a change class if certain prerequisites have been met.
I think for the purposes of the current state of the engine, we will need to have it be a separate class from the beginning.
