I think you pretty much named them all. However, there are countless other boutique shops who will custom wind for you if you send in your stock pickup. Some of them are quite inexpensive for the work they do, like Rose Pickups.
I have experience with Aero Mustang pickups, because I have one. I think it's a beautiful sounding pickup. It really thickens up the sound without losing any of its punch. It gets the bass to more of that P-Bass range, which means that solo, it's not going to be the greatest thing ever, but play with a band, and you'll be loving just how it always works. Here are the words from the maker himself:
The pickup is an exact drop-in replacement for the Fender Mustang Reissue bass, but has a better frequency response than the original. The string spacing is standard Mustang 4 Reissue, 18.00mm C-C. New covers are not available from Aero, but the new AeroMustang Reissue pickup will fit perfectly into the original Reissue covers.
The Mustang pickup is a hum canceling pickup, and therefore there is some loss of high harmonics along with the common mode noise (this is true for any hum canceling pickup regardless of manufacturer). The AeroMustang pickup has an output very similar to a PB (the compressed feel). The AeroMustang pickup uses a 1/4" diameter magnet, and this changes the articulation of the pickup (as opposed to a 3/16" diameter magnet).
All Aero pickups have a broad frequency response (good bass, flat mid, clear high), and a high level output (you will not need a pre-amp to boost gain). The frequency response of most Aero pickups is broader than that of the instrument. You can use any pre-amp with Aero pickups, but note that the frequency response of the pickups is better than any pre-amp you can install.Aero pickups will accurately convert the mechanical vibrations of your instrument into electrical signals. This means, if the frequencies are in the instrument they will also show up in the electrical signal.
So they are a lot like P Bass. Though the pickup is smaller than a P Bass, I believe using the larger magnet, as you would with Music Man pickups, helps provide greater punch, but it's not muddy because it's not an overly souped up wind. It's very balanced. Looks like it's $160 from Best Bass Gear.
Nordstrands, never tried. However, I have some experience with their pickups and I really can't think of any reason why I wouldn't try them. These pickups didn't exist or I wasn't aware when I was getting my Mustang upgraded, but in the current market, the Nordstrand is the one I probably would have chosen. As great as my Aero is, the Nordstrand NM4 is half the price at $80 from Best Bass Gear. That's a steal. I think my favorite pickup I've ever played is the stock neck pickup in my Ibanez 655, which is an OEM version of their P Bass pickup with angled poles, and their Mustang pickup has the same angled pole design. And given their reputation, you'd imagine their tone would be stellar.
The cool think about Duncan is that I believe that they're the only production pickup winder trying to do the Mustang Bass as close to vintage as possible, and not only that, they come with covers, which others don't include. So if you're building from scratch, they're probably the ones to go with. They're $160 at the custom shop.
So, to me, it's like this. If you want the most faithful pickup possible, either do a custom rewind or get a Duncan. If you want the best deal possible, Nordstrand. Aero is great, too, and I love my Aero, and I guess I recommend them if you really want that 1/4" magnet setup.
