Thanks for the feedback. I know remapping a basic vim key is pretty drastic, but to justify seek's speed I needed an easily accessed key--though I do plan to allow setting it to another key in your vimrc--and substitute quite fits the bill. I'm already using 1s instead of lone s without thinking. And for higher counts it doesn't get in your way.

Regarding the motions with d, c and y, just to clarify the seek motion is available anytime. As for the others, they work similarly to iw, i" &c, and I think these operator pending motions add a great layer of flexibility to vim without needing extra base keys.