All of the reasons you stated plus the fact that some people can't get soft furs is why I raise rats for my ball pythons.
I do raise soft furs for my corns, hognoses, sand boas and king snakes.
Everybody has heard stories of ball pythons getting hooked on soft furs, but no one that I have come across is concerned that a corn or hognose or sand boa or king is not going to convert to mice or rats.
From my experience you are going to want to have at least 2 males per breeding group. My reasons are because soft furs take a relatively long time to mature to breeding size, they are pretty territorial and sometimes they accidentally pass away for whatever reason. So, this will inevitably lead to a situation in which you have ready and breedable females, whose mate has passed, that can't have a new male introduced to them without them attempting to seriously hurt each other. If you are lucky the females will have a litter that you can allow a male to grow from and become the breeder, but because they take a relatively long time to mature it can have a large impact on production.
I would actually recommend like 2 males and 8 females in the rat rack style concrete mixing tubs and using the 10 gallon tanks as the grow outs. Different soft fur groups can be mixed safely and without worry of harm as long as the soft furs are introduced in groups and on neutral ground(clean bedding) and they are under about 12-15 weeks old.
I always have a third male juvenile soft fur in each tub as well just in case I lose one of my breeders.
I have 4 groups of 2 males and 8 females. I make about 300 soft furs a month.
I have to plan at least 6 months ahead of time when retiring older groups as it takes that much time to properly introduce litters from different groups, to keep from to much inbreeding, and then allow them to grow to maturity and begin to produce regularly. All the while holding back enough to feed my own collection.
It's a lot of work but I actually like them more than rats. If I ever decide not to keep ball pythons, and I stay with smaller snakes, I will probably give up the rats all together and just raise soft furs.