Here is my input on this up until my status in the Q course:
I am prior service and I was told when I re-enlisted I WOULD NOT get a bonus. I didn't really care,I was just happy enough to get the 18X contract.
SOPC is a bit of a smoker, but you do get a lot of good training and familiarization with the lay of the land

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I was informed by some PAC personnel upon in-process of SOPC that prior service 18X's ARE in fact entitled to a bonus if you enlisted before September of 2008. If this has changed or not, I do not know. The only stipulation was you had to get selected to get the bonus, where as the brand new recruits got theirs before even going to SOPC!
It's not about the money, and if it is for you, don't bother ingesting anything I have typed.
My opinion though, absorb all the training you can; it will help out in the long run. Just take care of yourself.