In what way? I find the lag on the iPad to be annoying enough that I've never bothered with it. I've never found any of the E-Ink devices to come close enough to paper to make me consider giving up paper notebooks - Though it's been about 3 years since I last checked them out.
Have you tried the current generation of iPad Pro? They claim a 9ms lag, and coupled with their technology for up-rezzing refresh rate and touch sensitivity when using the Pencil, it's quite a substantial improvement in experience.
That being said, the iPad Pro is clearly a high-end general-purpose device, with a price to match. The device that fits our pocketbook is always superior to the device that is amazing, but remains in a box in the manufacturer's shop because we can't justify the price.
It's better than any e-ink device for sure and it's competitive with the iPad Pro. I think the latter now has somewhere around 15-20ms of lag? So it's close.
But honestly they're different devices. Similar in many ways of course but different too. I don't think it's really apples to apples.
That number was calculated by taking a high-speed camera and watching how long it took the line to catch up with the pencil. They cheat on the metric by juicing up the prediction. You can see this by flicking the pencil and then picking it up -- the line will go farther than you intended. And if you change directions, the line will take more than 9ms to catch up with you.
Apple are cheating the 9ms lag measurement the way speculative execution and aggressive cache population are cheating performance benchmarks.
In general, this point makes me think of computational photography. If you have extra computing power, you can do things that are synthetic, but nevertheless real enough to deliver satisfaction, in real time.
The iPad Pro is not an e-Ink device, however since the OP was speaking of it being better than anything else out there _including other eink devices_, I wanted to confirm that "anything else" refers to devices like the current generation of iPad Pro.
