As a Tech, I read up on the heads just recently and yea, they literally tout some number near 3 billion "injection rate" or something. Going off memory on that so don't quote me. Then, I will say that's as a tech for over 8 months and 35 installs, I have never replaced a head. Not one. To boot, I don't know of any other tech of ours that's has had to. I'm sure there had to be a few times at least.
I replaced another model (different co) once and the guy said he had it for over 10 years and replaced heads over 200 times and the machine only worked for half that time. I figured he was exaggerating but but even at half that. Sheesh!