Vintage Day-Date

[Makash]

I would like to buy a vintage Day-Date. I found these two pieces:

http://www.chrono24.com/en/rolex/day...num=0&tab=pics

http://www.chrono24.com/en/rolex/day...num=0&tab=pics

The first one isn't really "vintage," it´s 2002 model, but it has nice blue dial, saphire crystal and newer clasp.

The second one is 1971, in very good condition. Beautiful black dial, plexiglass and older clasp. I really like the vintage feel of the watch.

The newer one is a bit more expensive, but that's not a big broblem. I would like to know if the newer is better - for example saphire crystal. Where are the advantages and disadvantages over plexi on the older model. Also movement. Is the newer movement better, like more shock resistant etc.? Next, the water resistance is higher in the case of the newer one - 10 bars vs 6. Why? is it because of plexiglass on the older one? And can i swim also with 6 bar rolex? Is oyster, so it should not be the problem, or yes? I read somewhere that the older models with plexi are also good for swiming etc. I would really apprecieate any answers, and sorry for my bad english :-)