Thanks for the reply.
Just to double check, I have recorded the sound (file will only be up for 24 hours):
Iris sound
It is not the most interesting of MP3s. Sound occurs at 0:11 and 0:22.
My firmware is 1.11, is that the latest? The iris performance does looks to be pretty good. I was half expecting it to be like some of the plasma tech I have seen, but it is certainly better than that.
Watching movies is fine as the res change happens once at the start of the session and once at the end (the default image from the receiver is lower). If everything stays at 1080p there is no issue, just a stunning image. Elsewhere, it gets a bit annoying with the PS3 switching back and forth depending on the game/OSD. On the plus side, no input lag for gaming that I can sense.
I am actually just at the start of the RMA process, as Optoma labelled my description for investigation/repair. I was just filling out the form and pondering whether I needed two, one for the lens and one for the unit. However, I don't really want to send the unit off for a week to have it come back the same.
Thanks.