Good thought on the turle knot. Also kudos for not calling it the turtle knot. I wonder if tying the knot in reverse on a down eye hook would also work. I would think so but have never tried it.

http://shoreangling4u.tripod.com/knotguide/id24.html

I like the down eye hook for fly tying. I tie a lot of parachute flies and the down eye gets the eye out of the way of the parachute hackle fibers. It also allows me to use the bobbin cradle on my Renzetti without the thread unwinding when I spin the hook. A straight eye allows the thread to slip more easily over the eye as the hook spins.

I also think a straight eye allows for more crowding of the eye of the hook when beginners tie flies. The hook eye angle seems to help keep thread clear of the eye, and the angle reminds the beginning tier to keep the area free for the tie off.