The INF pickups have always been solid middle-of-the-road pickups. Their shortcomings are typically due to being built to a relatively low price point and subjectively lacking a bit of complexity and character compared to more premium offerings, but they were certainly not "bad" pickups at all.
I've actually preferred a stock Infinity neck model to a Jazz in at least one guitar and the JB only won out in the bridge of that same guitar because it had a bit more character and was a touch quieter.
The INF line was designed to be a step up from the exceedingly basic "Powersound" pickups, but they eventually trickled their way down to more entry level instruments. I don't think it has ever been confirmed that the INF models were based on specific Duncan or DiMarzio designs, but some models certainly shared specs that resembled popular formulas (ex: 16.4K with A5 similar to a JB, etc).
To be clear, the INF line (as well as the Quantum pickups soon after) was NOT made by
nor designed by DiMarzio. That rumor has driven me nuts for years, but it's classic internet misinformation that got repeatedly shared until it seemed like truth. I suspect this was a result of DiMarzio's longstanding history of working with Ibanez and the fact that some of these pickups resembled popular DiMarzio's with their matte bobbins, dual rows of hex poles, etc.
In contrast to the Infinity/INF series, the DiMarzio/Ibz line was a proper premium-quality product made by DiMarzio in the USA and there were 2 iterations (in the typical 6-string format, anyways...a 7-string version based on the D-Activators was also produced).
The original "DiMarzio/Ibz" set, which was found in various higher end models over a number of years, featured a bridge pickup that was basically a hybrid of the Steve Morse bridge and a Super D. The matching neck was essentially a mildly tweaked Super 2. The second iteration of the DiMarzio/Ibz pickups was a lower output series created specifically for the SA line of guitars a couple years after the originals launched. I believe DiMarzio once told me what the SA models were based on, but I can't remember at the moment (they may have been proprietary, rather than a tweak on an existing model). You can tell the 2 iterations apart by looking at the pole pieces...the originals had dual rows of hex poles, whereas the SA versions had the standard slug/screw configuration.
Sadly, the original "DiMarzio/Ibz" pickups are some of the most counterfeited pickups out there! If you buy them secondhand, you have about a 25% chance of winding up with an authentic-looking set of counterfeits. Tip: If they don't have the white paper label on the bottom, they're most likely fake. I've seen sellers on eBay in the US, UK, and Australia purchasing these counterfeits for next to nothing and selling them secondhand:
LINK
