I bought into the "Fender bridges are crap" and have bought a few aftermarket bridges, Gotoh, and BAII. After trying them and comparing them to a stock Fender bridge, I'll save my money from now on and stick with the stock design, for the most part.
I replaced the springs with longer springs that dont rattle, because they are held under tighter tension. I put stainless screws on both bridges on my jazzes. My Geddy jazz barrell screws are replaced with longer screws to compensate for the different bridge mounting location. The Geddy jazz has it's bridge mounted just a little over 1/8" further back.
With the stainless screws and longer springs I have no problem with the bridge and get the tone I like. Total cost to mod both bridges was around 7 bucks.
The Standard jazz bridge has the threaded saddles and the Geddy has the newer single slot type. Both intonate perfectly, and stay were they are put. I run flats on both basses and just prefer the tone I get with the vintage bridge.
I gave my Gotoh 201 to a friend who needed one for a project, and I now have two BAII sitting in a drawer. Unless the bridge is actually broken, and that can be fixed very easily, by a trip to a hardware store. I would save your money.
IMO, while standard bridges may look cheap, they are quite strong and do what they are supposed to do. There is a tone difference. As far as it giving more sustain, I don't hear a problem with sustain from my basses. I can easliy pluck a note and hold it for longer than a count of 4, at a fairly even decay. How long were you needing to hold a note?
In the end it's your bass, and if a different bridge floats your boat, go for it!