I'm in disagreement with taking religious as Najd, but you're also dropping DotF. Note that in making the argument you are, you're essentially doing the same thing as Wiz

. 2 missionaries, like 5% strength, is *unique*. Najd has long been the top converter nation in the game, one of the few tags that doesn't have to give its unity much thought at all, especially since it isn't taxed by reformation spamming religious zeal. Religious, while a great group, is weaker on Sunni than most other picks too because of just how much Sunni you'll be bordering, neutering Deus Vult. I like rushing ADM/Influence sooner as a stronger play for Najd, even with the 2% strength of the beta patch.
Also, let's say you have 5 missionaries. Adding a 6th improves your conversion power by 20%. If you can convert provinces in 12 months, 6th missionary gives you another conversion every year. Extra % strength has to take that many months off your other 5 missionaries to match that. It's unlikely it can, maybe if you're converting really tough stuff and you're talking a whopping bonus like 5%. In most cases extra missionary will drastically outperform even 2% more strength, that's part of the reason non-Abrahamic faiths are trash for conversion compared to Abrahamic, they're capped at 3 missionaries even with religious instead of 6-7.