Hi! My daughter was put on the Enfamil AR Lipil when she turned 7 months. I had been breastfeeding, so the sticker shock alone was discouraging to me. She, too, was on Zantac & Reglan. The formula was a big help for her weight gain.
I found the best way to use this formula was to make a batch in a pitcher using a wire whisk to stir it, as it is very thick. I would leave it in the pitcher and only pour out what I needed. I used playtex nursers and actually poked holes (with a sterile needle ~ heat over lighter flame and then push through the under-side of nipple through the hole) in the biggest size nipple the made.
As far as heating the bottle, because it's so thick, you'll want to start heating about 15 minutes before the feeding. A pain, yes. But compared to a vomiting, smelly baby, it was worth it!
I only had to use the Enfamil A.R. Lipil with my daughter until she was 10 months. I was then able to switch her to regular Enfamil until she turned a year, when she could have whole cow's milk. They outgrow the GERD/Reflux eventually, but getting to that point can be a strain! My daughter is now 2 and is as happy as can be.
Our son, 9 months old, has just been put on Zantac (as of yesterday) due to his spitting up/vomiting. He's on regular formula and I use Dr. Brown's Wide Neck bottles with him. He doesn't cry and scream after spitting up like our daughter did. But he's not gaining weight properly... I'm just crossing my fingers that the Zantac works and we don't have to take more aggressive actions towards it!
Best wishes!!