I agree. It would be great to see some revenue numbers, if it's really successful (which I think it is), it would be a nice model for other developers or software companies.
I think the nag dial is just about right between casual use/unlimited evaluation and I'm using this editor for real shit.
Case in point: WinRAR, anyone?
EDIT: Just to clarify, I like the pricing model too. I just don't think it works for software in general.
I point out winamp because it is similar in that no new features are unlocked after paying.
That is, it's not like, say, Chrome release where it's Dev -> Beta -> Stable. It is (was?) more like Nightly -> Dev -> Beta/Stable.