Found this on another av site.........
"....I have also found out the difference with the sx4280d and the rest - basically it is technically identical to the 4280xd and just has a cosmetic difference in that part of the surround is aliminium instead of matt black plastic. I'm told it IS a UK model, released a couple of months after the 4280xd.
The key difference (and why it is cheaper) is that is does NOT qualify for the 5 year pioneer guarantee, you only get the standard one year. Apparently this is a marketing ploy to sell them with a lower ticket price - although once you add a 3rd party 5 year warranty, the price isn't so far away from some dealers prices for the 428XD......"
It would appear the differences are cosmetic. Hope this helps to put the old man's mind at rest.