Not many are Sys, and I cant imagine why other than AEROs are custom made to you, not stocked by folks( as they are custom) , and a bit spendier than most pups. Look, I'm likely a better "audiophile" than bassist these days, but these Aeros are special, they truly are. Flat response and reach lower than any other pup I've tried. Its easy to make a mid humpy pickup, that's how they wind naturally. Some basses sound pretty dull acoustically and need that hump. A good one doesnt. To wind one that stays flat an reaches down to 20Hz is a small miracle. They make a 5 string bass breathe deep!
I may be wrong about this, yet beleive AERO introduced many of these soapbar styles years back and were the original suppler to Fodera. I think now they supply Elricks, which like Foderas , are such well built instruments, you dont want pickups coloring the natural sound.
One reason I may order some for my "new" Fender Aerodyne in basswood. It has such a strong deep natural voice, the stock pups muddy it bad to my ears, esp the P pup ( its P/J) . I know it would gain both depth and articulation with custom wound AEROs. And I know the engineer, Larry Pollack, likes to build P bass pups! ( he can make a p bass pup in a J body which is pretty cool and was the FIRST to do so.)
Anyway, maybe not the known "shelf space" brand, but how can you argue with making Foderas and Elicks sound as good as they can ? If its a worthy instrument, give the folks at AERO a ring, being mindful of Hawaii time, and explore for yourself. Dont take my word for it, yet I do trust my ears.