Typhoon, some good tips there! I knew that the siwash hooks have a bigger eye but I never thought of the angle that the hook would ride at. Good to know.
Question: is there a "difference" between the straight siwash (such as the Gamagatsu I usually buy) and the offset siwash like the Mustad Ultrapoint? I have heard some guys say that the straight siwash are better for colorados and other light spinners/spoons as they don't affect the action of the light lure. In other words they glide straight through the water. Whereas an offset siwash, so I'm told, will affect the action of the lure. However I've heard with bigger/heavier lures, say a 1/2oz spoon, will not be affected by either hook, so choose what you like.
I have also heard that the offset siwash are better at holding a fish on, although I'm not really sure why. I've never tried sickle style hooks (siwash or any other type). Personally I have not noticed a difference in fish retention between straight or offset siwash hooks on my spinners, spoons, etc. I generally just buy the straight silver Gamagatsu if I'm swapping out trebbles, replacing fouled singles, etc.
Lastly, I'll share a tip I learned from the TV show Fishful Thinking that has improved my hook up rate. It pertains to swapping out the trebble for a single hook on flatfish lures. I always just cut off the trebble, put on a split ring, and then added an appropriately sized siwash hook. However, as Charlie points out, now your hook is riding sideways through the water. Not great for hook ups. The sollution? Use two split rings together off the flatfish. When adding the siwash hook make sure the hook point will point up. I switched all my flat fish up this way and noticed I lost very few fish, whereas before with only one split ring the fish were flipping the hook often and I couldn't figure out why.