I'd upgrade them to ceramic bearings (about $90), but you can go with better ones than stock for around $40.

The Mavic hub has a loud engagement from the snappy pins hitting hard. I take it as a sign of safety, but some people don't like it. No more sneaking up on people while coasting...

I have never needed a reason to go with a cassette higher than Ultegra... maybe I don't know what magic lies with a Dura-Ace, but I'd go with an SRAM red cassette at that price range.