R494D is nothing more than a 2.5 to 3.5 adaptor.
So it works in Optiplex 320, 360, 380, 745, 755, 760, 960, 980, 3010, 3020,7010, 9010 etc.
While I agree with you about just a simple 2.5" to 3.5" adaptor, not all adaptor are made the same. I've bought two different types of adaptors and they don't fit properly, the adaptors tend to be a bit wide and the four side screws don't fit in properly, this is why i'm looking for a adaptor that would fit perfectly as I have 40 computers to upgrade.
The adaptor you recommended is slightly more expensive than R494D, the R494D is just under £10 on ebay.
I recommend going for the Item that is least expensive.
There is no advantage to either as its a passive piece of plastic and metal. Since I don't live in the UK I would not have a reference as to what is cheaper.