Personally I think that starting over is a good idea. With my own tree I'm starting a new one that only goes along my own line directly. In other words to begin with I'm not going to add any siblings, cousins, etc: - just parents, grandparents etc: as far back as I can get. Then, when I've got all of those added with the correct information, sources, citations, etc: I might go back and add other relations.
Meanwhile, I'll leave the other tree with all the information I gathered last year just as it is now.
Regarding FTM, I always keep a copy of my Ancestry trees on FTM and update it each time I make a change. It's always good to have extra copies of things and, if you want to, at least you can work on FTM offline.