Here is the deal with burn-in(image retention is a better term) with FEDs...
AFAIK, all FEDs use phospers, so, as is the case with CRTs and Plasmas (which also have phospers) there is a theoretical chance of burn-in/image retention....
I say theoretical because even current gen plasmas (which at one time, was the display tech most suspectible to phosper burn-in/image retention) don't have problems with burn-in...
For all thier pros, on possible con with FEDs is image retention, in theory...
People didn't squeal about burn-in with CRTs because they were cheap and easy to replace...plasmas are some of the most expensive TVs available, noone wanted to replace a 5000+ dollar TV, hence the squealing....
From what I understand, burn-in will be a non-issue with FEDs, but we will see...
Keep in mind, FEDs are, for all practical purposes, fancy CRTs....the best CRTs ( like the $35,000 Sony G90U, for example) offer the best picture quality today, though the gap between it and the best DLPs and LCOS displays is quickly closing...
Carbon Nanotube supporters claim their FEDs will offer the best picture quality ever...
If they can mass market these things and get them down to the prices they claim (<$1000 for a 60-inch HD panel) then I don't think anyone will make a big noise, even if they *DO* have problems with burn-in/image retention..
