Burning at 16x takes roughly twice the time as burning at 48x. A 48x burn doesn't burn at 48x all the way, it starts at about 20x and increases until it reaches 48x at the end of the disc. A 16x burn on the other hand burns at 16x all the way, so the difference isn't as big as you would think. Whether you have the time to wait twice as long is something only you yourself can answer.
If you don't know what jitter is, chances are you are not an audiophile so you probably wouldn't be able to hear the difference anyway. Jitter is a slight variation in distance between zeros and ones on the media, and with some Digital-Analog converters that variation will get through to the analog signal sent to the speakers, and trained listeners can sometimes hear this on high-end audio equipment.
As rdgrimes said the difference between burning a full CD-R at 32x and 48x is about half-a-minute, and even less if you don't burn the full 700MB or 80 minutes. If you burn an entire 100-pack spindle at 32x instead of 48x and burn 80 minutes on every one of them, you have still only used 30-40 minutes extra time.
So IMHO you are overreacting somewhat with your negativity over the NEC 3520's inability to burn your Sony CD-R media at 48x. Please get some perspective.