Althugh most of us use the bow anchor roller, I agree that this is not the best way to attatch a rode. You are far better off using a snubber line, to a cleat directly on the side of the boat. This way there is no chafe on the main rode--since few if any C Dories have all chain, the snubber and chain hook don't necessarilly apply. However we use snubbers tied on the nylon 3 strand rode with a rolling hitch. This allows adjusting the point of chafe, changing chafing gear etc easily in a real blow. On our larger boats, we always used a snubber, which never took the load on the bow roller.
As for the weight of a storm anchor--yes, we generally like a much heavier storm anchor for the "ultimate storm" but the fluke area is also an extremely important consideration--maybe even more so than weight. In larger boats I used to say that the minimum size plow should be 35 lbs. That is way too heavy for a C Dory.--it is also very difficult to store.
The solution can be a light weight anchor which breaks down--such as the Fortress FX 37. This anchor weighs 21 lbs, breaks down for easy storage and will hold up to 3000 lbs. It is comperable to a 35 to 50 lb steel anchor in holding power (comperable bottoms, ie sand) This is what we carry on the Tom Cat 255 as a "storm anchor" On our larger boats we had anchors up to 150 lbs (but they broke down into 50 lb sections)--and 1/2" chain (weight 2.5 lbs a foot, or 50 feet weight was 125 lbs additional weight, plus 1" diameter rope--in other words, you don't only have to increase the anchor size, but also the rode and all gear associated with it).
We like the 7 : 1 scope--this has been well established, based on the Danforth type of anchors, to give the best shot at both penetration of the bottom and maintaining a downward migration of the anchor shank during a load. The anchor shank needs to remain parallel to the bottom, the fluke angle is 32 degrees in Danforth and Fortress anchors, and the rode angle with the shank needs to be 8 degrees or less. Remember that the "depth" includes the distance of the bow off the water, plus the depth of the water. There are some instances where we will set with a 7: 1 scope, power back and check for dragging, and shorten up scope if there are other boats nearby. However generally we stay with the 7:1 scope which is recommended for combination rope and chain rode--10:1 recommended for the all rope rode and 5:1 may be fine with all chain, until it begins to really blow.
As for the ball as a shock absorber; this is more likely used in coral infested waters, where there is a chance of the rode being entangled under a coral head and severed. Also a large bouy can hold the "weight" of the chain and keep this from depressing the bow--allowing it to rise more rapidly. All in all, one needs a longer rode to do this, because the float tends to effectively bring the rode to the surface before the bow of the boat. We have used this effectively in open water where there were coral head (for example we anchored on the Salvage Islands to dive on wrecks--pretty much out in the open and used this technique). It is not something I would use every day, especially with a C Dory. But it is a "Trick" which might help in some cases, to releive the strain on the boat.