I have around 15 leviton dimmers/switches and they have been working great for about 1 year. Personally I would stick with Z-Wave plus, it was a good bump in overall performance, range and energy. With a custom device handler I also can change the fade on/off time, brightness at power on, LED status, min/max levels and other settings all from the smartthings app. I have had good luck with the Cree Par30 bulbs and I can dim down to about 1-2% with no hum or flicker.
They are not cheap normally so I check when I am in HD for sales and have been replacing them over time. Last week I found some at my local HD for $5 a bulb which is crazy cheap. You have to check your local store, because online is just retail price.
I also have some philps LED bulbs that work great.