I was worried about the same thing. One owner here did tell me something interesting, if they can digest bone, they can probably digest substrate. And they're masters at getting stuff out of their mouth.
As far as the feeding response goes, as long as you handle them more than just feeding them, and you set a strict feeding schedule, you should be fine. I feed mine a large rat every other Thursday around 5 pm. Although they can't tell time, they can see routine. If I pick up the tongs and take out her hide, it's feeding time. If I only lift the hide up, and don't take it out completely, I'm just holding her. Most people with rack systems feed in the snakes living enclosure. Moving them to eat can just stress them out.
When I got monty I had the same fears, because she had been fed in tank. So the first feed, I took her out and put her in a feeding box, and she ended up regurgitating. I think it's just unneeded stress. Although in your head, moving them makes sense, to them it doesn't.