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If I were you, I wouldn't worry too much about the life of your internal DVD drive. That's what is there for, to handle usage, or heavy usage, if needed. Isn't that why we spend so much money and invest into these machines in the first place?
Even if your internal dvd drive does go bad, you can simply buy a replacement one and if you are up for it, install yourself. It is a very simple thing to do, there are plenty of self-install videos out there.
The web-site I'd go to buy a replacement internal DVD drive is OWC (Other World Computing =
Performance Upgrades; FireWire USB SATA Storage; Memory, more at OWC) They even upload the videos to show you how to install it yourself and save yourself some money.
You can also look into buying their external DVD drives, or even Blu-Ray read/write external drives all-in-one.
Again, you have an internal DVD drive for a reason. Use it, abuse it if you have to and if it ever breaks down, just know that the replacement for an internal DVD drive is relatively inexpensive. CHeck that web-site out and you'll see for yourself. Hope that helps... ...