Just a critique on CD drive failures (including DVD drives...)... I worked at a surplus and saw many failures.
"True, the main reason being is the stress they can be subjected to. IIRC optical drives can spin at up to 10,000 RPM"
Not a problem. I only ever saw one drive that had a spindle failure. I did see one CD that had cracked inside the drive and did a fair bit of damage.
"Plus the laser is guided on a screw that can wear over time"
I saw only one or two drives with a seek failure.
" and the 'laser' itself is nothing more than a cheap diode behind a piece of moulded plastic."
Yup, cheap optics. I found the LG (and Goldstar before that) drives were the worst. Sonys were also quite bad (despite being a LiteOn mechanism, Sony's firmware made the drives suck -- I "fixed" one or two by flashing LiteOn firmware into them!)
I think the thing that helps LiteOns is good firmware. If they don't like a CD, most drives handle it by either 1) Locking up, sometimes a drive'll lockup up until you hit eject, sometimes it just trys to read "forever" (i.e. until the computer is turned off). or 2) Trying to read a CD at like 48x for about 2 seconds then giving up (either returning a disk read error, or claiming there's no CD in the drive). In contrast, the LiteOns will try reading at high speed first, but if that doesn't work it'll try reading clear down to 1x before it spits out CD read errors. I found one where the "CD brake" had failed, and instead of spitting out a disk that was still spinning at high speed, it actually just did a huge ~20 second pause when I hit eject so the disk could slowly spin down to a stop.
I did burn out one of my LiteOns, I burned like 10 DVDs in a row and overheated the burning laser! Next DVD I got "laser calibration error" and not even a mark on the disk 8-). I think my favorite failure was one model that'd read a CD fine in a straight line, but if the CD was thrashed a lot (like when an Ubuntu LiveCD boots...) after about a minute the drive would start mis-seeking... but instead of giving seek errors, or just taking longer to seek, it'd just start returning whatever the laser happened to be pointing at. (Luckily since virtually everything on the Ubuntu CD is checksummed, it'd realize straight away something had gone wrong.) That wasn't just one unit, I had the same thing happen on like 4 or 5 examples of the same model! Ouch!