I noticed on one of my custom hybrid longbow (built by highly reputable bowyer) the limbs are 0.28" near the tips vs 0.25" near the middle. What are the advantage of using reverse tapered limb laminations vs normal tapers?

A true reverse taper would equal a parallel limb. You may have a tip wedge in there. You would need to ask the bowyer his design thoughts on why he uses a reverse taper. A more consistant bend will come with a reverse taper. But you will have more mass limb weight. I suppose you could go with a deeper core and narrow the tips more and make up some of the difference.

If the tip has height, the width can be smaler as the height goes in the formular as a square value.

There are no tip wedges. Its a very gradual taper from tips to mid limb where its thinnest then it gets thicker again at the fades. I guess stiffness is a reason for the thicker tips as I noticed the limbs don't bend in the outer 1/3 but instead act like levers. I know there are other great shooting bows made with normal tapering cores. Just trying to weigh up the pros and cons of each design. Thanks.

He is trying to get the limb to bend in a particular place with that type of taper. I am sure it has to do with efficiency for that particular design (At least it does for me).

some guys are grinding the tip wedge right on the lam-so it may be built-in and not visible

Yeah sounds like a double lam sled setup and maybe sort of static tip design.

You got it Crooked Stic....Nothing new though. The older Martin ML-14`s longbows w/ all Zebra Lams and handle had similar tapers.