should i get a big bearing or small?
If you want snappier, tighter binds, go with a small bearing. If you want a large gap for multiple string layers, then get a large bearing. Those are really the only differences you have to worry about now.
What are the bearing sizes compared to the dark magic?is it bigger or smaller?
and whats the difference in play with big and smallbearing compared to the dm.
I can’t help you with your questions but you can try using the search box (you’ll find plenty of topics). Oh and btw, please avoid double posting, you can just edit your post with the Modify button. 
sorry
The Large bearing is the same sized bearing as your Dark Magic. The small bearing is a Duncan sized bearing (Size A) and is obviously a good deal smaller.
It’s cool 
id say large
thanks you. now that i know the sizes i think ill go with the large 