The only speed gears I've ever tried that are any good at all, are the ones made by ABR. I think they're Delrin or something. I've abused the bejesus out of 'em and they don't fail. M-Chassis carries them, if and when they're available.

Can't say I know anything about the Eagle ones, but given the quality of their other product (that I've seen) I wouldn't bother.