ok apart from being lost on why eating rats is worse then mise (unless your mum owns rats as pets that is, my mum used to own mice and it took her a while to get usd to seeing my corns eat them) the only bad thing about feeding a snake food like that is when you first feed then and the smell can sometimes be a lil overpowering but you soon get used to it (I did anyway)
I own 2 corn snakes one I have had from hatch ( youngest) and the other from about 1 year old (older one) both are fine. The younger can be a bit grumpy at times but all he does is move to the other side of the tank under his hide is he doesnt want to see you. HE's only even gone to bite me once and that was my own fault (I aslo own a cat and she didnt like that i was playing with the snakes and not her so she decided to use her claws in the back of my knee to get my attention, took me by surprise i lost my balance and smaked my head on the tank while i was still holding onto him, luckily he wasnt hurt just a but spooked but still struck at me just to let me know he wasnt a happy snakies lol)
My oldest is as docile as you want she will happily just go you sleep while your holding her or sit drapped over you shoulders for hours. So from my experience I would never say corns are a bad temptered or anythng.
I dont own any ball pythons personally (not my type of snake to be honest) I have been around some and they again are also good natured snakes (unfortuneatly the 2 i view had also be obviously mistreated as I could see burn makes on them, I went to view then after seeing an ad in the local paper, odd really as theses 2 pythons were advertised as a single boa constrictor, the place was a tip too i couldnt afford to buy the poor things however upstair I could also see some very very thing dogs ( i wasnt aloud any further then the front door) se when I left I phoned the RSPCA and they sorted it all out) but they were very placid snakes (altho their fussiness in eating is one of the things that put me off)
Ok as for the tank I cant get my brain around the idea of working in gallons for my corns i use a 3' x 1.8' x 1.8' with plenty of hides (altho most of the time they would rather be out lol)
To be honest if your local reptile 'expert' is also the person your buying the reptile from then from the sounds of it he can either make more money off you buying a ball python or he alot more pythons then corns in stock atm.
With the whole thing of snakes being skittish its all in truth down to the snake and its history. No two snakes are the same.
ops this ended up longer then I planned sorry guys lol ><