I have been told not entirely suitable as when carbs run a bit rough they will add to the rattle of carbs as opposed to rubber that cushions and you may get damage. However I was told they are good for track cars or if you keep your car in very good tune. Iwould love to hear from someone who has the aluminium mounts.
I'm also about to use them (fairly long types some 6.5cm in height). I'm aslo skeptical on this...why alfa didnt use something similar and uses always rubbers? did has to be something like thermal transfer to the carbs? more over, what is happening with all this weight ,alu mounts+carbs+ air box cowl + heavy original top cylindrical euro filter box? after all these, the carbs staying bracket -down to engine mount- must be used anyway? any ideas or experience?
The aluminium mounts do the supporting so you don't need the air-filter support. The flexibility comes from using MISAB or O rings and thackray washers and lock nuts. The carbs do not get bolted up solidly. I have the Alfaholics gear and ran the car from London to Milan and back with no problems whatsover.
I would guess that it's a far more expensive production solution that the route Alfa took which is why they used the rubberised mounts and paper gaskets.