It is easier to change the weight by using different amounts/size of
split shot, or sink putty etc. the disadvantage I believe with split
shot is that it gets hung up easier than a weighted fly

You may already know this, but one way to cope with that is to leave a
long "pigtail" on your tippet when you tie it to your leader. Then
tie a half-hitch at the end of the pigtail, and another partway up
toward the knot. Attach your split shot between the two knots.

The lower knot is to keep the split shot from slipping off. The
upper one is to weaken the tippet material so it will break at that
point if the split shot gets hung up, saving your fly.

vince