Ive used the Leica SYOOM extensively, which is not nearly as smooth as Toms products.
Ive also used one of Toms Winders on my old M4-2, one word, Awesome!
As for weight, I have pretty big hands, the added base height improved handling for me, and the added weight I never could feel in practice.
Also great for wearing gloves in the winter.
Honestly, I used the cameras advance more often then the lever winder.
Do you plan on buying one new?