The main reason for prop deicing (heat or chemical) is to prevent prop vibration if one chunk of ice comes off on one blade. Apart from the vibration issue, deicing the prop offers practically no performance benefit in icing.
TKS prop deicing offers a small side benefit as IO540 explained, but it would be a waste of time weight and money not to go to the full TKS system since you would already need the pump, reservoir, timer etc anyway.
On a certification test of the T210, rate of climb with no ice was 900fpm; with boots and prop deice 700fpm; with boots only 500 fpm, with prop only 200fpm; with no protection 100fpm at sea level. With TKS the airplane would have been practically ice-free.
Even in a strong, turbocharged, known-icing certified twin pneumatic boots won't do the job as I experienced on a dark night at 4000ft over the North Sea.