Re: hollow fleye?
I have tied and cast them. They cast pretty well, although I will admit I was not able to throw my longest cast with them. Their hollow construction causes them to compress while flying through the air, making them have a front profile pretty similar to a deciever.
The main thing I noticed about its castability was its shuttlecock like behavior. It flew just fine when up to speed, but wanted to slow down rapidly as it neared turnover. This tells me I would want to do one of three things: use a leader with a long butt to kick it over harder, use a short leader so the energy from the line doesn't dissipate as much, or add some weight to the fly so it will have more inertia on its own.
I should also add that I was casting the thing with two abnormal variables thrown in. I was throwing it into a 15-20mph wind, and on my nine weight. the flies were tied on a 2/0 hook and about 6" long.