When Does Your Opinion Cancel Out The Rest?

I am a member of a crit group on AQC and my group is fantastic-as is the site(writers-go check it out :) ) I also recently gained two crit partners from Query Tracker(another good site) and am swapping chapters with them. My purpose for wanting to have wonderful people to critique my MS is to make sure I have it polished as best I can.
I have been working with my group for a few months now and just recently began re-writing my beginning and adding more to my middle and end-based off feedback I got from my group. The re-write feels better then the way my MS was before, so I am glad I listened to them.

Last week, I posted my first 3 (new) chpts for the ladies to have a look at and they said it was better but there were still some issues they had-some of them even wishing I had kept something from my original that I had decided didn't flow right with my re-write. I listened to their advice this time as well-went back and read through to see what I could fix/add in. The missing section that they want, may not be plausible-but I worked on the rest of their suggestions. I don't know about the (new) chpt 4-6, I posted those yesterday so we'll see.
I also swapped my first chapt with one of the two people from QT-she basically said my entire first chapter sucked(aside from a journal entry I have at the end of every chapter) She said i needed to completely scrap the first chapter and re-write...which I have already done once. ( I have not gotten any feedback from the second person reading it, but *fingers crossed*)
So, my question is this-when is it time to say, "you know what? I am done changing my entire MS to please everyone else.?' When do you accept that there are going to be things in the MS that not everyone likes? How do you determine what is strictly the one sighted opinion of someone, and what is what others(readers/agents/publishers) would agree needs fixed?
The answer is simple, sort of... You stop taking their advice when you truly feel it is time. Listen to your heart and head, both because one can easily mislead the other ;) Take suggestions from others, consider their opinions-and I mean really consider them; then ask yourself, "What fits/works best in the story I wanted to tell?" If you change your MS over and over based on the things your crit partner or beta reader says-it's not your book anymore and then what's the point in that? I write because I love to write. I have a story to tell and I want-no I will tell it. The fabulous women in my crit group are observant and smart, and I am sure they know what they are talking about...but I wrote the story, it is in my heart-so I know better than anyone.
When does your opinion cancel out the rest? When you truly know that your MS is yours. When you read through it-completely objective(no attachments because how will you know that you don't want to change something just because you are attached. You have to be positive that you are not ignoring advice simply because you aren't willing to change something-even if that something would make it better) and you can say-I like my story as is, this is the story I wanted to tell, and it is right-for me. So, think about it next time you have feedback from someone-really think about everything-and you will know when enough is enough.