I'm not sure what you're asking here. Are you asking if you are up 100% or more on TD Bank if the decision to sell gets harder? Let me know and I can give a better answer.
Ultimately that is a difficult question to answer as it is really dependent on someone's personal situation. However, what I can certainly say is I have watched plenty of people hold stocks on constant spirals downward because they don't want to pay taxes, only to lose more on the drop of the underlying holding than they ever would have paid in taxes.