Just curious, why bitcrack? If you want to improve upon anything, I would suggest to look at VanitySearch. It already handles multi GPU and is faster. The issue is reading full address, but works with partial/strings. It already does what bitcrack does, and faster, just full address issue.
Just a question.
Because I can just paste the Int class from Kangaroo to VanitySearch to provide an initial speed boost while Inwork on other things

On the positive side though, I did manage to replace the Misaligned access error with an Invalid Argument error, I think that one should be reproducible in a debug environment.