I registered here to post my experience.
I found this thread after looking to see if anyone else is having the same problem, so here goes.
I bought my TW3500, the UK version of the Epson 8100 in February after waiting years for a good 1080p projector at a decent price point, with good enough bulb life and acceptable bulb price/availability (these are critical).
What a projector it is, awesome in every respect, except one, bulb life
This projector gets used a lot, around 16hrs a day so problems will undoubtedly crop up faster.
At around 700hrs bulb life (nearly all ECO mode), the picture started to flicker.
The flicker didnt happen on high power mode (that I could see), only in ECO mode.
The bulb got progressively darker but I assumed it must be normal behaviour as its hard to tell what is too dark.
At around 1500 hrs I emailed the store and told them it was too dark, they said I should contact Epson.
Epsons support centre was hard hard work, I had to phone multiple times to make sure I was being told correct information, they devised new ways of getting me to go away each time.
So I ended up asking, then demanding to speak to a manager but non was available. I explained that isnt possible in such an environment, so he told me someone would call back.
No one called back so I phoned again a bit annoyed and within an hour of the call a manager called me.
He said an engineer would come some time within 2 days but he couldnt say on which day or what time.
I accepted being happy I was getting support.
The next day, the projector became extremely dim and not long after there was a very loud bang!
I called Epson support and they told me I need a new bulb.
They didnt have stock though and were not able to tell me when they would have stock.
Baffled, I asked them how they had no stock of probably the most used bulb and no way of knowing when they would get stock, but they seemed just as baffled as me.
Eventually they agreed they would have to send an engineer and give me the bulb from his projector.
I was not happy with having a second hand bulb but they assured me it would be brand new, so I agreed with gritted teeth.
I pushed them to give me a time and the engineer turned up within a couple of hours!
From reporting the problem (to a manager) to the engineer turning up took only 1 day, that part of the service is fantastic but I sure had to work for it.
The engineer replaced the bulb and my new toy was better than ever, even brighter than when I first had it.
(The old bulb had exploded but because it is surrounded by a wire mesh, it was well contained in the bulbs shell)
The projector has been awesome up until a couple of days ago, at 870hrs (nearly all ECO mode) the new bulb has started flickering.
I havent contacted Epson again yet and really dont want to after the trouble they gave me last time.
As I've already had my warranty replacement bulb, I'm expecting to be given a tough time.
This will be interesting, I'll keep you posted.
I dont use the auto iris.
The auto iris can mask the flickering so if you use auto iris, turn auto iris off and see if it flickers in ECO mode.
Its easier to see the early flickering when viewing brighter images like a PCs web browser.
There was no flicker in either bulbs early life.
The projector does its own power down cycle and has always been shut down using the remote control, not from the mains power.
The filter has been kept very clean.
Projector is mounted halfway up a wall, central to the screen, there are no nearby heat sources.
Edit: 8th July
I received a reply from the store I bought it from.
He said 'this is not a common problem with Epson, I suspect there may be a fault with your unit.'
Maybe this is true, I just dont want to contact Epson now until I absolutely have to.
It looks like you get a better first response from Epson in the US so dont let my UK experience put you off over the pond