Flying DFW-CLT today, F full, I had set up both an ExpertFlyer seat email alert and a Notifly alert on my Android.
Notifly alerted first and I was able to snag the seat up front. (And without guilt, I was #1 on the upgrade waitlist anyway). I guess I got it in between ExpertFlyer checks, because I never got an email from them until 3 hours later, when a different F seat opened.
The best strategy, if you don't mind just a little extra effort, would seem to be to use both.