As it turns out, I discovered that I can vomit. I have had two stomach viruses post-Nissen and vomited once during each of them. As soon as I vomited, I began taking anti-nausea suppositories to avoid stressing my wrap.
I can burp as well. I was able to burp in the hospital immediately after my surgery. My surgeon told me that I wouldn't be able to vomit or burp, but I believe he did that in the event that it was the case. I've read here of many who can both burp and vomit.
Because of my stomach's ability to burp itself, I never had much bloating even in the early stages.
I wouldn't rule out being able to do these things post-op, as many can.
Good luck with your decision!