1) When typing in the search field in the toolbar, perform the search instantly, without the need to press enter. This makes it much easier to see when having typed enough, and when a correction needs to be made. Much like the Windows 7 start menu basically.
2) Also pressing Esc to clear the search field, and revert to the normal folder view.
3) Optionally, when starting to type anywhere in the program where text normally cannot be entered, focus the search field to type it there. Much like the Windows 8 start thing. Currently the search field isn't accessible at all by keyboard :/
4) Only when the option in (3) is enabled, when pressing the up or down key, focus the entries pane to select one without having to tab there. Alt+Down would still open the dropdown of the search field.
5) Finally, configure what the Enter key should do instead. For example, it could copy the username for the first search result. Shift+Enter could copy the password of the first search result. This should probably be configurable.
When all these are implemented, KeePass is more search-oriented for those who like that, without destroying existing functionality.