The writing latency isn't bad at all. It honestly feels like writing on paper with a really good pen. Latency is noticeable if you're actively looking for it, but it doesn't affect writing at all.
The quality though isn't ideal. All of the Remarkable devices have terrible issues with screen calibration, so the line you're writing doesn't match where the stylus is. Also lines tend to be jagged or fuzzy.
Writing latency on the current generation of eink devices is good enough not to be noticeable.
I've found latency when changing pages to be rather frustrating to the point of it being difficult to land on the page you actually want to be on.
wrt to remarkable: changing pages indeed does take a little time, thus it's not good for researching. writing is nearly instant, but not perfectly, so imo it's not quite as good as on paper (although the resistance is pretty nice). One personal note: I would love to have a thicker pen, the pencil-size is not mine.
Still, I like the device (I'm one of the old customers so don't know about how the subscription or non-subscription fares, since I am grandfathered in) but it's clearly not for everyone. Also I really love the eraser function of the newer pen.