I'm currently using Vrapper, and it's been a year or two since I tried Eclim. But as I recall, it's a question of which is primary.

With Eclim you get all of vim, as you say, but you lose a bit of the native eclipse editor functionality.

With Vrapper you get all of eclipse, and a subset of the core vim commands. It's not vim, but you get to keep all of the features of the native eclipse editor.