I have bought ex-dem a few times with success and a good discount.
Best was Krell KRS200s upgraded by Krell to 400 watts per side. They were only one-third of retail around 1991. They were about 4 years old then. I had them re-furbed incl replacing all the caps around 2008 at a cost of £3,500. They are going strong.
Also Martin Logan CLX Anniversaries at about one-third off retail in 2012. Last year I had them cleaned internally by the importer, one driver and some caps replaced, £1800. They are now like new.
And yes, I would take the 802 D3s. I had the original 801s (bought new at inception of the model) for many years before the MLs.
Ex dem may be better than second-hand as you buy from a dealer and get a warranty. A good way to buy high-end stuff safely and save $$$$$.