I haven't looked into it recently but yeah, like I said I was trying to find the sweet spot with pen latency and price. The iPad was cheap (~$350) and had great pen latency, whereas the reMarkable was not cheap or as full featured, and the Surface was also not as cheap and had reports of bad pen latency (e.g., see https://www.reddit.com/r/Surface/comments/e8kho9/if_there_is... for an example)

Update: It appears the situation has improved across the board. https://www.tomsguide.com/news/the-remarkable-2-is-an-ipad-p... says 20-21ms is pretty standard now.