fischee,
If you haven't already, please discuss this with your doctor.
As for my thoughts on the subject...
I've been on and off of so many meds it's not even funny.

My doctor informed me, although I already figured this out due to personal experience, that getting back on a medication after you've already been on it before lowers the original efficacy of said medication. Of course, this is not always the case for everyone, but it's a confirmed norm.
Been on Zoloft myself, and like you, it didn't do a thing for me, other than make me feel absolutely nothing. No emotions, just numb, making me an utter wreck. Tried several SSRIs and SNRIs, and had the same results.
Personally, I like your tapering schedule. Klonopin would minimize or hopefully stop you from feeling any adverse side effects (e.g. headaches, tremors, etc) you might experience as you come off the Zoloft. If your anxiety were to increase once off the Zoloft, Klonopin's great for A. Then if you decide to, taper off the Klono next.
First get rid of one, then the other, so on and so forth...at least that's what my GP has always advised, and thus never experienced horrible withdrawl symptoms when changing meds. But as always, when changing medication combinations or dosages, I stay in
constant contact with my doctor, usually seeing her once a week or once every two weeks during the process.
Best wishes to you as you change med regimens and such!
xoxo
[Edit: I thought that maybe I should note that I have partial epilepsy, so my GP monitors me very closely during med changing processes to decrease my chances of having a sz.]