I used to do this and i had no problem with my Mac!!!
This laptops are "dogs" they dont lag or crash what ever u make them!!!
And for the quality i think it was prety nice!!
I had a very good quality from the recording and the mp3 form wasnt bad!!!
I dont know any other why to record from Traktor bcz i have the same problem so i dont sit to find a solution bcz i have 1!!!