You would think so, wouldn't you? However, those Quadras were built to last. I used to burn CDs in an old Quadra 610... the key was lots of RAM and giving Toast at LEAST 16 megs of cache... especially if other things were going that could require CPU cycles (file sharing, printer sharing, etc.).
I plan to install a burner in my 950 just as soon as I get some free time and find my old copy of Toast. Now if only A/UX had support for burning CDs...