There is one consistency among all converts. They are all happier than before. I've never seen someone who met God and wasn't happier after he met Him than before.
How many believers have you surveyed in this regard (rough estimate), and of which denominations? Have you made inquiries at ex-Christian, ex-Muslim, ex-Buddhist or similar sites? Former believers testify to being extremely happy when they successfully free themselves from those beliefs, even if religion initially increased their happiness. How do you explain this phenomenon?
That wasn't exactly what I was looking for, however, as happiness can come from a vast number of non-religious sources. It's a subjective and internal process that could easily be imagined into being and cannot accurately be quantified. I want to see something objective and tangible that happens to all
seekers, as consistent and pervasive as gravity, and clearly linked to a god and to no other possible cause.