SplinterGroup
Yeah, the screw gives fine adjustments, but I like how you clamp the block to the fence for stability.
I'd say set it up, make a test cut and if a bit too fat, just add shims and reclamp.

SplinterGroup....I just had to share this...I came out to my shop about 15 minutes ago. Grabbed the 1/4" jig and clamped it to my fence. I made no adjustments to the set screw after setting it up yesterday. 
WHOAAH!! I ran though two 27" maple lengths. It was stunning! They came out smooth and consistent over the entire length at 0.249" diameter. 
I'm very happy. 😀