In short: I notice no difference compared to the original batteries – and you probably can't praise a replacement battery any higher. They last just as long, behave totally inconspicuously in the camera's menu, and the A6700 doesn't complain about "unsupported accessories" at all. By the way, I've also used the batteries outdoors at −8 °C, and even in this cold, there were no dropouts or noticeable performance drops. That speaks for itself.
The set also includes a charger that makes a solid impression. Compact, lightweight, fits effortlessly into any camera bag. The charging speed is rather moderate, though. The device draws a maximum of 1.8 A at about 5.15 V. Doing rough math, an empty NP-FZ100 with approximately 16 Wh capacity needs just over two hours to charge—and charging two batteries simultaneously takes correspondingly longer. For my daily routine, this is not a problem. I have three batteries total and haven't yet managed to drain them fully in one day. However, if you film for hours every day or require fast charging times, you should get a more powerful charger.
All in all: SmallRig delivers a package here that doesn't have to hide behind the original. Good build quality, excellent runtime, fair price. And above all – no surprises. Exactly what you expect from a battery.