I did some research. I looked up the subject in the Owner's Manual (surprise! this subject is mentioned) and I spoke with the service manager at my Nissan dealership this morning. He's a nice guy and so am I...so he was willing to take time to talk to me about this subject after I explained why I was asking. So, in case it's helpful in reducing someone's angst, here's what I found:
[Excerpt from Murano Owner's Manual Page 5-13, 2012 edition]
If the engine is very hard to start in
extremely cold weather or when restarting,
depress the accelerator pedal a little
(approximately 1/3 to the floor) and while
holding, crank the engine. Release the
accelerator pedal when the engine starts.
If the engine is very hard to start because
it is flooded, depress the accelerator
pedal all the way to the floor and hold it.
Push the ignition switch to the ON
position to start cranking the engine.
After 5 or 6 seconds, stop cranking by
pushing the ignition switch to OFF. After
cranking the engine, release the accelerator
pedal. Crank the engine with your foot
off the accelerator pedal by depressing
the brake pedal and pushing the push-button
ignition switch to start the engine. If the
engine starts, but fails to run, repeat
the above procedure.
As for the input I got from my service manager, here's what he said (paraphrased, but based on notes I took while he was talking):
"Engines are engines regardless of whether they have the Intelligent Key (IK) system or not. The IK system just tells the starter motor to engage for as long as the key is pressed (limited by a safety override timer). If there's anything wrong such that the engine is harder to start (e.g., temperature, gas quality, battery voltage, etc.), the IK system cannot overcome it; in this sense the IK system is exactly like a regular key switch.
We sometimes have complaints from customers (particularly new ones) who imagine all sorts of things about the IK system...mainly I think because it can seem like such a mystery to new users. What we train our team to tell customers is to patiently try the start process again if the engine fails to start after cranking for a few seconds. We also explain the instructions to press the gas pedal down a bit if the engine seems to be "hard to start" in warm or very cold weather. Most of all, we tell customers not to worry if their engines don't start instantly every once in a while. Only chronic hard-to-start conditions are actual problems. In those cases, we know what to do to try to isolate the cause (i.e., run a report on the car's ECU to see what error codes were recorded).
Random episodes where a few seconds of cranking is required are no big deal. I suspect that the gasoline quality (i.e., contaminated with water, not low octane) is the root cause. Strangely, even though they occur infrequently, the random episodes seem to worry new owners the most. What I try to do is be patient and explain that if the car had the old-fashioned manual key-start switch, this so-called problem would present itself in exactly the same way. The usual concern seems to be that the IK system is somehow defective or the engine is in, or about to enter, some failure mode. Unfortunately, it can be hard to get people to overcome their fear of the IK system, particularly if it is new to them."
There. I hope this is helpful to someone. If not, well, at least it was free.