LaI agree too. Two screws is a major improvement. But, there are also solutions for scopes with only one screw. I have had zero problems with loosening on my 883 since I landed on well fitted Kirk (and others) arca swiss plates with lips and no rubber on the base. Rock solid. If you don't have metal to metal - will the new two screw system loosen?
I have quite a few cameras. They are all equipped with Arca plates attached with just one screw. They stay put permantly and are rock solid. However these plates are specially made to fit each camera, cannot twist and it always metal to metal contact.
My long tele lenses are equipped with Arca replacement feet, also specially made for each lens. Rock solid. Metal to metal.
Arca tailor made plates for cameras and lenses from suppliers such as RRS, Kirk, Markins etc. are usually very good. Rock solid, do not twist and can stay on permanently. They are also Arca compatible, which some suppliers such as Swarovsky and Sirui cannot be due to custom ”improvements”.
Unfortunately similar Arca plates for spotting scopes are not manufactured. They are all generic! To overcome this limitation all sorts of solutions are used. Plates with lips or pins to prevent rotation are e.g. used. I have tried most of these ”solutions” including a big 3/8” scew. I am not impressed. Some improvement, yes, but not good enough for a permanent installation. In reality, my scope plates with just one screw have to be tighted rather frequently. It seems I have to live with that it but I am always looking for a better solution.
Two screws combined with decent hardware is a big improvement, but so far only Kowa 99 offers that.
Swarovsky nowadays seems to deliver their scopes with Arca feet. Unfortunately they are very short and they offer a clumsy balancing rail to overcome this obvious shortcoming. What a mess. I am all in favour of factory istalled Arca feet, but then it has to be implemented properly. Real Arca without stupid custom features etc.
My experiences with rubber and cork are not good. Perhaps good enough in some cases, but not good enough for permanent installations. The used materials and glue ages. E.g. the glue may start to act like a grease and the rubber moves around. The little flex allowed seems to make the screws work loose.
I realize my quest for a solid connection is influenced by the fact that I require my tripods and heads to work not only with a spotting scope but also with a camera and tele lenses. It has to work both for photography and spotting scope.
