Because of this thread, I paid more attention to iris noise last night. It never bothered us on the HomeCinema Pro, and it doesn't bother us on the 5030, and our PJ is directly above our seating position (maybe 6ft overhead). The only place it really stood out was in massive brightness switches -- typically commercials, where you'll go from a white background logo-and-legalese screen to an all-black screen. Then you hear the iris whirring around up there -- and it probably seems worse because the audio typically drops out at that point. But usually the audio drowns out any lens noise. I find I have to focus on the noise specifically before I notice it.
The iris is slightly less noisy than it was on the older Epson (and the fan noise is virtually nonexistent on the 5030, whereas the old one sounded like a passenger jet taxiing around up there).
It's highly subjective, but honestly I'd have never even thought about it without the constant discussion. But again, I'm far from the pickiest AVS user. Consider this the "average consumer" viewpoint. I set it and forget it.