Logan had his nissen done at age 18 months. Seriously, it was the BEST thing we did for him, this boy was in pain and misery every single day of his life up until his surgery - sure, his pain was controlled with losec and ranitidine but the discomfort of constantly vomiting made him very miserable, it is a rare photo of him where he is smiling. Logan was tube fed due to reflux + other issues and he showed no interest in food, once he had his op he began to try foods, it was another 2yrs before we got him fully eating though.
Now he is 7 1/2, has vomited twice since his surgery, he can burp now, up until 8 months ago he couldn't. I have no regrets about putting him through surgery, his scarring is barely noticeable

Good luck with your decision making, happy to give more info if you want.