I really like them. The polycarbonate sticks in the tree well. The friction of the plastic on wood seems greater than nylon and the thinner walls give a bit of spring against the tap hole. They seem less likely to split the tap hole and may be a bit more forgiving on a slightly out of round hole. Not that I ever have any of those. They hold the drop well. We push on by hand in the shop ahead of time without trouble. We still have some bags and the 45 fits through the hole in the holder and flange holds empty bags on on windy days.
I don't think the 45° angle makes any difference in flow, but overall they are the best spiles I have used.
John
2x8 Smokylake drop flue with AOF/ AUF
180 taps on sacks
75 on 3/16 tubing with shurflo
Eden Prairie, Minnesota