Let me throw this thought into the mix.
Regarding the SRH and SBH, both are fine guns that will serve you well for your entire life....and probably the entire life of your children.
If I had to pick one or the other (I own a couple of both types) I would have to say that I prefer the Super Blackhawk, specifically the bisley hunter variant. The hunter model has an integrated rib on the barrel which gives a bit of extra weight to tame the recoil and allows the easy addition of either a red dot sight or a scope if you prefer (scope mounts are integral to the barrel rib). Additionally the shape of the bisley grip seem much more akin to shooting high power loads than either the double action shaped grip or the typical plowhandle grip of the single actions. On recoil the bisley grip tends to split the recoil between straight back and upwards (A SRH comes more straight back and a standard plowhandle seems to be significantly more upwards). There is a reason that all of the custom smiths who turn out the really big boomers (475 Linebaugh and up) are building them with Bisley grip frames.
When hunting, quick reloads are never a concern so the single action does not really give up anything to the double action. For follow up shots, I find that I can follow up with nearly the same speed between the Super Blackhawk and Super Redhawk. Recoil will be the largest factor in this, cocking the hammer is secondary.
Regarding the caliber, I would have to recommend the .44Mag over the .454, mostly due to the fact that .44 Mag ammo is far more common and available if you don't reload. Also unless brown bears are on your list of quarry, you don't really need the power of the 454, and even then a hot loaded 320gr hard cast .44 Mag bullet would work quite well.
If this happens to be your first big bore gun then the 454 could be counter productive in that the heavy muzzle blast and recoil could easily cause you develop a flinch that could be quite difficult to get over. Using 45 colt loads in a 454 is certainly possible, heeding the above advise about cleaning between 45 colt and 454 loads, however unless you are buying specialty loads from places like Buffalo Bore, Grizzly, etc... a standard 45 colt load is sort of anemic in that they are made to shoot in the old Colt SAA guns.
I am pretty sure the sticky extraction in the SRH is more of a function of the type of steel used in the cylinder for the 454 and 480 variant and not an indicator of cylinder strength. In order to be able to maintain the SRH as a 6 shot revolver Ruger went with Carpenter 465 stainless as opposed to the traditional 410 stainless used on the 44 mag and smaller guns. The 465 stainless is a significantly stronger alloy however it does have more elasticity than 410, thus as mentioned, it does expand then contract back to the original size. This more or less can cause sticky extraction with the higher pressure 454 loads. Other 454 revolvers don't typically suffer from this because they are 5 shot variations with standard 410 stainless cylinders. AFAIK the SRH is the only 6 shot revolver chambered in 454
