I'm not sure something like the Kona Smoke will be significantly better than what you have.
Ditto. Running slicks on a mountain bike will put you easily as fast you'll probably do it with even a
road bike IMO. My commute is 14 miles one way and I'd use a mountain bike with slicks in a heart beat -- they're great commuters without the knobby tires. I am of the opinion that they're even better than most road bikes for it, because the bigger tires you can run at lower psi and they give a much more smooth ride over crappy roads. You can also usually install fenders too. And a rack and panniers.
I'd keep what you have, maybe upgrade your tires (which makes a HUGE difference) and get some good lights if you ride after dark (or before light).
The smoke is a good commuter, but it won't be any better than what you already have most likely.
I commute on a steel touring bike and get passed by people on mountain bikes with slicks commonly.