Life's too short to worry about a device if you feel your tone isn't what you expect. We all have different tastes, so it could be that you just aren't feeling the Kemper.
That said, download the trial of the Neural plugin, dial up some tones and then profile them with the Kemper. (Not sure how ethical that is, now that I think of it)
After you're done, play the plugin, play the Kemper and see whether you still have the same opinion.
The advantage of the Kemper is that you already have it, it is portable, and you can use it in a variety of situations.
The plugin, on the other hand, requires you to cart around a laptop and an interface.
In the end, no one can take the call for you. I've also had periods where I felt the Kemper wasn't doing it for me, but I always bought another one down the line, because it is a very handy tool to have.