Duncan Custom/Jazz in RG1527
All right, enough time has passed that I can make an educated case for this pickup combination.
1st, the installation of the Custom bridge/Jazz neck combo was a pain in the ass. The screws on the underside of the pickup had to be clipped because the body route of the guitar was so shallow. Second, the dog ears of the pickups had to be altered to fit as well. They had to be bent and shaped to fit the mounting dimensions of the guitar. This was not giving me a good vibe to start out with.
2nd, once the pickups were in, I played around with it. First impression: the Jazz pickup is the best neck pickup I have ever heard and it will be going in all of my neck-humbucker equipped guitars from now on. The Custom was a decent pickup and compared well to the Distortion and JB pickups I have in other guitars. The lower output took some getting used to, but the notes were all very crisp and clear sounding.
3rd, after playing with it for a while, I adjusted some of the individual pole pieces for each pickup. This only made the Jazz better and more defined (still the best neck pickup in my opinion). Now on to the Custom, it screams! The lower register has a well defined sound even when under heavy distortion. The lead notes are clear and bright without being too bright (think of a lead tone similar to the Distortion with a little less bite).
This pickup combo is a winner in the RG1527. The only downfall was the install problems. If you can get past this, then I highly reccomend the Custom/Jazz for your 7-string needs.