I would put the N4004 below the N50. It had a generation older technology (AF and metering) than the N50.
The N80 body can be cleaned with some careful scrubbing (clean lint free cloth...like an old t-shirt) and 70% isopropyl alcohol. There are several threads that you can look up to see how to clean the stickiness. Sadly this effects the N80, N90, F100. Not sure why, though.