Water buffalo. No choice in my mind
The curl is a great advantage over the straight horns but gemsbok is easy to process. Gemsbok won't give you much thickness or width. Both qualities that you want in your horn....especially for your first few bows. All the strps are vitally impoprtant and thinking you can skip processes will lead to a wonky bow one way or another! If you haven't made any hornbows before I strongly suggest not trying to re-invent the wheel haha....just follow the tried and tested methods worked out over thousands of years.
The poisson effect will end up straining the edges of the limbs significantly, whilst the center is loafing and can cause problems (lifting sinew etc) because of the uneven strain on the back, it can also split your belly horn. It would be a problem with the TBB bow because unless you went over 100# the limb would be very thin. Very thin limbs don't have much wood in them and the wood is what gives everything its side view shape and the bows stability largely comes from the wooden core. More wood more stability (assuming you cut the thing out perfectly straight and weigh your sinew bundles for perfect spacing of sinew.....).
HLD made from wood will not expeience the poisson effect to a negative level. Wooden bows can't be pulled far enough for it to matter, use any cross section you like with wood because at 1% strain it won't come into play.
Picture to follow fellas
