What Stub.. said.
Here's a bit of history. DiMarzio was one of the first - if not the first - to offer aftermarket guitar pickups. Certainly they were the first to do it on a grand scale with commercial success.
Way back when - in the early 70's, they were all the rage for the high output they gave. This was ok, because everyone wanted high output and nobody was concerned with good tone (or so it seemed). At that point in time, DiMarzio's customer service, for lack of better terms - sucked royally. They were not only top dog, they were the only dog. You got DiMarzio, or just stuck with what the manufacturers were giving you.
At that point in time - you could get a replacement Strat or Tele or whatever from Fender. No winding differences, just "replacement" for the one they made that failed. Same thing with Gibson, with one little plus - Gibson actively promoted their pickups for sale, for refitting to other guitars. They sold the rings, screws and pickups - but the pickup was only two flavors, Humbucker and SuperHumbucker. DiMarzio offered more flavors, and the same pricing as Gibson (more or less).
I gotta tell you - having called and spoken to folks at DiMarzio a few times in the mid and late 70's.... whooboy. Talk about "take it or leave it". At one point in time, I remember a conversation about the finish on pickup covers, nickel or chrome. I forget which, but I think... I wanted nickel and they offered chrome only, so I was asking to see if they ever heard of using the guitars original cover on their aftermarket pickup. Their attitude was - why should we give a crap about your question, or help you to find out if their cover will fit our pickup. Er... because I wanted to "buy" one of their pickups? The call ended with them telling me "I really don't give a damn if you buy one of our pickups or not <click>". I didnt' buy it.
Times change, and DiMarzio got noted for a really bad tone, in light of the other pickup makers (including Gibson) when the Super Distortion rage ended. What was left was DiMarzio holding the bag on bad tone at the expense of clever marketing and high output. To this day, there is a strong opinion from old timers (like me, I admit it) that DiMarzio = high output, bad tone. I know thats not the case, since they offer many many different pickups to suit lots of flavors. But, you get an old timer and tell him you just stuck a DiMarzio in your guitar and watch the sour look of consolation develop on his face.
Times change again. Now there are lots of boutique and semi-boutique makers. Gibson offers lots of flavors, Duncan has more flavors than Howard Johnson's, and DiMarzio does too. They have no doubt increased their customer service, and attitude in the last 35 years (I hope the guy who dissed me has moved on to the pensioners home....
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I still dont think the market share for DiMarzio is too great. They are growing, doing better, but Duncan is clearly in control of the market. The boutiques make it hard to offer something different. Many times - they (anybody) dont have something different, just market it with the right sizzle.
I tend to stick with very proven and reliable offerings, avoiding fads if at all possible. I do like the Phat Cats, but I'm not sure if they're a fad or a new classic.
Just my 2c worth