Like Chris said, it does help performance,2-3 fps in my design. If you use a reverse taper, it moves the bend thru the whole limb whereas the tip wedge only stiffens the tip.
Making the tip stiff bends the limb a little more in the midlimb,somewhat reducing string angle,and for lack of better term,adds leverage when the limb returns . Mine are 4-5" inside the string nocks with a .009" per inch taper.
You can also manipulate the bend away from the riser with a power lam,basically the same deal on the other end at the fades. Mine run out 3 - 4" past the fades with a .009" taper.
I have started grinding them with the .001 taper on the belly so I have 4 less things sliding around in the gluey mess! LOL
Oh, after grinding, the tip and butt get run thru the sander without sled to parallel the very ends down to a bendable thickness of .080 or so to help in fitting the riser. I forgot to do that on one bow,it took some xtra wedges to make those .144" thick butts fit those riser belly ramps!