An Eclectus can still fly pretty darn well even with a wing clipping because of the size of their wings. Also, most groomers won't clip an Eclectus to drastically because of the weigh and size of their body. The same goes for African Grey's.
I see on Craigslist every now and again in my area where either an Eclectus, African Grey or Macaw has flew the coop. The Owners even put in their ad that the birds wings had been clipped. They may not be able to fly for long distances, but far enough that they could get out of sight.
That is why I will not take Mac or Tiki outside unless they are in a travel cage. But I have been considering a harness though.