I used the Brodak Y&O 12X4 & 10X4 on my Webra 50 & Webra 32 respectively yesterday. I ordered two of each and two 15X4s for my ST90 on my Ecstasy. They said that the 15X4s were not available despite you can order them off of their website. I ran the 12X4 on my Webra 50 with Mac Header & tuned pipe mounted on the Wacky-Bee III. The Y&O doesn't quite pull quite as well as the 12.25X3.75 APC, but makes up for that in throttle response. RPM is comparable if not slightly higher over the APC. I got the same throttle response as the Zinger 12X4 (modified and un-modiifed). So I'd have to say, the Y&O has my vote! <GRIN> By the way, the Y&O has an awesome sound to them, it sounds like a Bolly at high RPM . Guys with noise restrictions may have a problem with the Y&O.
I tried the 10X4 Y&O yesterday as well on a Webra 32 mounted to my PBXL. I can't say that I really got to test it though. It was windy out, and I put it into an inverted flat spin from a hover about 1 foot off of the ground. By the way, the inverted flat spin was not on purpose The wind blew it over. I didn't recover too well this time and sacraficed the prop. The other 10X4 they sent to me would not balance (luck of the draw).
As an overall, I'd highly recommend the Y&O for Fun-Flys.
Kevin