The JB is such a ubiquitous pickup that it still winds up in many players' Gibson style guitars. It's certainly not unique enough to be anything special. It sounds like you just got the Duncan Hot Rodded set and dropped them in your guitar like many guitarists do. Guys like blueman have tried it all, and while I wouldn't always choose the same pickups he would, he's probably tried a lot more pups in an SG than you or I ever will, and my experience is mostly in line with his. It's not just about what's classic or not. It's about the best recommendation for the poster of this thread. He's free to try the JB, but he's most likely not going to audition everything in the Duncan catalog. He's got to start somewhere. Any other pickup mentioned here is a better place to start. The JB would be towards the bottom of my list of pickups for him to try. Worth a shot, maybe, but not if you've can only try a few.
Neither do you
But we're trying to steer him in the right direction. He's free to try the JB if he wants. I did, even after being advised not to, and I thought "Well, I like it, but I guess they were right. I like the Custom and 498T a lot better in this guitar." A lot of my favorites bands get great sounds out of a LP or SG with a JB in the bridge. And after I tried it, I now wonder how much better their tone would be if they had tried a few more pickups instead of just going with the usual aftermarket swap. Actually, I wonder how many would settle on the JB at all after first trying out of few Customs, the C/59 hybrid, PG, or Screamin Demon.
That hasn't at all been my experience, and that's the first time I've heard that. I found the JB in my SG much more like how you're describing your perception of the Custom. I don't hear people calling any of the Customs 'ice pickey', but the JB gets called that a lot. And there are other variations of the Custom to try out, almost all of them well suited to SGs. Not to get an even EQ at all, but to get prominences in difference frequencies to lend them different flavours.
Because an amp's tone stack is a fairly limited tool for shaping your signal. You can dial out some highs if your top end is harsh, but the harsh quality could be coming from the pickup or amp itself. What if you want the same amount of high end, but want it smoother? What if the frequency you want to tweak isn't what one of the knobs controls? And you can't dial in what isn't there to begin with. Pickups are one of the things you can swap out to get your signal the way you want it before it hits your amp.
So how many pickups have you really tried in your SG?