aero86, i have a super crappy cheap plastic one. i dont actually use it for fletching cuz cane aint exactly a flat surface to glue to. it does, however, comein handy for marking where your feathers need to be so you get them spaced evenly.
sorry, not trying to change the topic.
as far as the fletches go, im not sure of the difference between offset and helical, but i would believe that straight fletches would be faster and quieter, but anything that adds spin would be more accurate.