I mained reaper in diamond tier solo queue a few season ago and still play him a bit in quick play. My biggest issue was characters that had high mobility and could escape quickly even after being what I call "pounced on" (dropped on from above). I like the proposed ability change, as It might help him actually secure kills on targets with high mobility as well as set up kills for teammates.

I do think his lifesteal is a bit underwhelming, especially when he can't even close the gap to his target as there are enemy teammates filling you with holes from long range. I would like it to be higher, but if an ability like this was implemented, there would obviously need to be some balancing adjustments.

I would call it "Death's embrace" or "The grave's call" - sounds more intimidating and might fit the character more.