i have a dm12 coming in the mail and its stock and i was debating the same thing. check out youtube, there's a handful of BW bolt reviews. summing up from all the research i did, the only noticeable difference is the gun will shoot a bit more consistently, and i guess the carbon sleeve looks cooler? im going to break my dm12 in and tune it to perfection as much as possible this season, and once i know the true performance capabilities of the dm12 i will decide if its worth it or not. im leaning towards no.