As Jaden's Nana said, I believe that each person will react in their own way. But no, I do not believe - in any way - that you would even come close to going back to a Day 1 situation. I ended my "90 day" session with Champix (as we call it in Canada) yesterday, after lowering my dose to 1 - 1mg pill a day for a week or so. That wasn't prescribed, but my doctor said that as long as I was feeling OK, go for it.
Since there is no nicotine or "addictive" substances in Chantix, there is no chance of withdrawals. Ah, but then, read around the internet. There you'll see the horror stories of being on and getting off Champix. It'll make for fun reading, especially knowing that YOU are bigger and better and stronger than those folks.
Believe in yourself and what you are doing. The rest just gets easier.