The biggest problem I see with the retaining axle is it would reduce the mount's ability to absorb the vertical motion created by the piston's travel, transmitting that vibration to the airframe. The advantages you list over the Hyde mount are really not an issue anyway. The engines don't move forward, nor do they wobble during high G maneuvers due to the nose ring on the engines. It's no different than your mount actually in that respect. With the Hyde mount, you either have the nose ring on the airplane, like with the AR variety, or the nose ring is incorporated into the mount, exactly like your mount, with the ARI version.

Chip has some mounts with over 3000 flights on them without failure. The Hyde mount is certainly the standard to compare against, and with so many people using them for so many years, I think it's pretty hard to say there is anything 'wrong' with their design. Merle charges the prices he does for his mounts because they're all hand made, by Merle himself. It's his labor going into the mounts. IMO, they're the best pattern mount there is, with solid evidence to prove that over the last 15 years.

That being said.. Roberto showed me his mount when he was here in the USA at the TOC, and it's very nice work. I don't doubt it will work very well.

Doug Cronkhite