I did a couple weeks of EEN last year. I had flared badly, lost 17 lbs in a month and was having diarrhea 20+ times every day. Could not digest anything - literally anything I ingested, including Ensure, went right through me and caused horrible gut cramps along the way. After a month of that, I ended up being admitted to the hospital for 5 days, and during that time they put me on IV steroids and EEN (Vivonex specifically). I think it was a combination of the steroids and the EEN, but it did get me feeling better. Fortunately I could digest the Vivonex a lot better than the Ensure! After 5 days, they discharged me with oral steroids and a prescription for 2 weeks of Vivonex. Unfortunately, my insurance wouldn't pay for it, and it was over $600 for a 2-week supply.
Because of the exorbitant cost, I couldn't afford to stay on EEN for longer than 2 weeks - if I could have, then I would have preferred to stay on it longer (as it was, my parents gave me the $600 just so I could afford that two weeks' worth). But, even so, I was able to successfully wean myself back onto bland, low-FODMAP solid foods slowly and carefully after the 2 weeks of EEN. The cramping and diarrhea didn't return. I know I can't attribute my success wholely to EEN, because I'm sure the steroids played a part too, but in my experience it was worthwhile and seemed to help a lot.
I will say that elemental formulas tend not to taste delicious. Vivonex tastes... well, not like food.
They fool you, the packaging says that Vivonex is made by Nestle, so initially you think it might taste like chocolate. Nope, it's pretty much the exact opposite of chocolate. It's hard to describe the taste but it made me think of horses and wood chips for some reason - it's like drinking a barn, if such a thing were possible. Even so, I grew accustomed to the taste and even came to crave it, so I think that means it was really doing good things for me. I still find that I crave Vivonex from time to time (just writing this post, I'm thinking about the taste and drooling, wish I could have one right now! It's disgusting yet wonderful, it's really odd).
I will also say that I did obsess about food while I was on EEN - the nutritionist or dietician or whatever she was at the hospital, she told me that when I started eating again that I should start with low-FODMAP, so I obsessively looked over what the acceptable foods were and looked up recipes and made shopping lists and looked at ingredients lists. I thought about it all the time during that 2 weeks that I was on EEN. So keep that in mind - it is really hard to stick to a liquid only diet that tastes kind of like a farm, especially when the people around you are eating normal food that looks and smells amazing. My advice would be to stay away from grocery stores, restaurants, and even other people at mealtimes, because it tends to drive you a bit crazy when you're on EEN. I would have to go into another room when my husband was eating, it was so hard just to be in the same room as food. It's hard to stick to EEN, but it's also definitely worth it in my opinion. Good luck and keep us posted if you do EEN!