My experience was exactly the opposite of Emily's mom. You can read the entire thread here at OCF TSA and Air Travel
Bottom line: you should be able to bring your Ensure with you.
From another forum on feeding tubes, it appears that the experience is different with every airport but everybody reported issues and delays. Dulles was annoying but nowhere near as foolish as Albuquerque. At the worst, it's just a hassle. I did have a complete doctor's note but the TSA automatons didn't bother to read it not even once. At least they should be familiar with Ensure unlike the prescription Jevity. The TSA web site also says there is a special line but not at IAD nor ABQ.
Don't let it discourage you from your trip since it definitely doable.
Charm