For consistency it's hard to beat a spinning reel. The line peels off the spool without any spool drag each time it's casted. Same can't be said for conventional casting reels where thumb pressure, salt, debris, and even lubrication breakdown can greatly effect casting. If there is no level wind on a conventional reel that may pose a problem as well where as with spinning outfits there's no need to level wind. Casting distance has always been a hot topic between spinning vs. conventional guys. I think the nod goes to "well prepared and maintained" conventional reels. The "slap" that occurs as line peels off a spinning reel and "slaps" against the guides creates friction and reduces efficiency. It's a difficult if not impossible process to engineer from happening. Conventional reels peel line off straight with minimal drag on guide surfaces.