Depending on how much you’re relying on DEVONthink searching, you could find it really lacking in Keep It. Keep It supports some handy functionality in searching. You can whittle it down to just searching names of notes, natural language dates, etc… However, I know DEVONthink does a great job of surfacing notes based on how you interact with it with other notes. Gives relevancy ratings. Has the ability to search around “phrases” (find all notes where I wrote Airmail within 5 words of Workflow).
I have never needed that power, but if you are a heavy user you might miss it.