I found it kind of surprising that up to this point no one has mentioned burning in. Given that the IE800 is coming from Sennheiser, I'd hold my firm belief until at least 100 hours have passed on your pair, james444. Hopefully bass will settle down, soundstage will open up and the treble will get a bit more refined.
I believe that materials undergo changes with use over time, but it's funny that the changes, WRT to headphones, are always positive.
Not really trying to stir up an argument, I just find it intriguing.